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Li Y, Jiang W, Mellins ED. TCR-like antibodies targeting autoantigen-mhc complexes: a mini-review. Front Immunol 2022; 13:968432. [PMID: 35967436 PMCID: PMC9363607 DOI: 10.3389/fimmu.2022.968432] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2022] [Accepted: 07/06/2022] [Indexed: 11/13/2022] Open
Abstract
T cell receptors (TCRs) recognize peptide antigens bound to major histocompatibility complex (MHC) molecules (p/MHC) that are expressed on cell surfaces; while B cell-derived antibodies (Abs) recognize soluble or cell surface native antigens of various types (proteins, carbohydrates, etc.). Immune surveillance by T and B cells thus inspects almost all formats of antigens to mount adaptive immune responses against cancer cells, infectious organisms and other foreign insults, while maintaining tolerance to self-tissues. With contributions from environmental triggers, the development of autoimmune disease is thought to be due to the expression of MHC risk alleles by antigen-presenting cells (APCs) presenting self-antigen (autoantigen), breaking through self-tolerance and activating autoreactive T cells, which orchestrate downstream pathologic events. Investigating and treating autoimmune diseases have been challenging, both because of the intrinsic complexity of these diseases and the need for tools targeting T cell epitopes (autoantigen-MHC). Naturally occurring TCRs with relatively low (micromolar) affinities to p/MHC are suboptimal for autoantigen-MHC targeting, whereas the use of engineered TCRs and their derivatives (e.g., TCR multimers and TCR-engineered T cells) are limited by unpredictable cross-reactivity. As Abs generally have nanomolar affinity, recent advances in engineering TCR-like (TCRL) Abs promise advantages over their TCR counterparts for autoantigen-MHC targeting. Here, we compare the p/MHC binding by TCRs and TCRL Abs, review the strategies for generation of TCRL Abs, highlight their application for identification of autoantigen-presenting APCs, and discuss future directions and limitations of TCRL Abs as immunotherapy for autoimmune diseases.
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Affiliation(s)
- Ying Li
- Department of Pediatrics, Divisions of Human Gene Therapy and Allergy, Immunology & Rheumatology, Stanford University School of Medicine, Stanford, CA, United States
- Stanford Program in Immunology, Stanford University School of Medicine, Stanford, CA, United States
| | - Wei Jiang
- Department of Pediatrics, Divisions of Human Gene Therapy and Allergy, Immunology & Rheumatology, Stanford University School of Medicine, Stanford, CA, United States
- Stanford Program in Immunology, Stanford University School of Medicine, Stanford, CA, United States
- *Correspondence: Wei Jiang, ; Elizabeth D. Mellins,
| | - Elizabeth D. Mellins
- Department of Pediatrics, Divisions of Human Gene Therapy and Allergy, Immunology & Rheumatology, Stanford University School of Medicine, Stanford, CA, United States
- Stanford Program in Immunology, Stanford University School of Medicine, Stanford, CA, United States
- *Correspondence: Wei Jiang, ; Elizabeth D. Mellins,
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Yamamoto TN, Kishton RJ, Restifo NP. Developing neoantigen-targeted T cell-based treatments for solid tumors. Nat Med 2019; 25:1488-1499. [PMID: 31591590 DOI: 10.1038/s41591-019-0596-y] [Citation(s) in RCA: 138] [Impact Index Per Article: 27.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2019] [Accepted: 08/22/2019] [Indexed: 02/06/2023]
Abstract
Stimulating an immune response against cancer through adoptive transfer of tumor-targeting lymphocytes has shown great promise in hematological malignancies, but clinical efficacy against many common solid epithelial cancers remains low. Targeting 'neoantigens'-the somatic mutations expressed only by tumor cells-might enable tumor destruction without causing undue damage to vital healthy tissues. Major challenges to targeting neoantigens with T cells include heterogeneity and variability in antigen processing and presentation of targets by tumors, and an incomplete understanding of which T cell qualities are essential for clinically effective therapies. Finally, the prospect of targeting somatic tumor mutations to promote T cell destruction of cancer must contend with the biology that not all tumor-expressed 'neoepitopes' actually generate neoantigens that can be functionally recognized and provoke an effective immune response. In this Review, we discuss the promise, progress and challenges for improving neoantigen-targeted T cell-based immunotherapies for cancer.
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Affiliation(s)
- Tori N Yamamoto
- Center for Cancer Research, National Cancer Institute (NCI), National Institutes of Health (NIH), Bethesda, MD, USA.,Center for Cell-Based Therapy, NCI, NIH, Bethesda, MD, USA.,Immunology Graduate Group, University of Pennsylvania, Philadelphia, PA, USA
| | - Rigel J Kishton
- Center for Cancer Research, National Cancer Institute (NCI), National Institutes of Health (NIH), Bethesda, MD, USA.,Center for Cell-Based Therapy, NCI, NIH, Bethesda, MD, USA
| | - Nicholas P Restifo
- Center for Cancer Research, National Cancer Institute (NCI), National Institutes of Health (NIH), Bethesda, MD, USA. .,Center for Cell-Based Therapy, NCI, NIH, Bethesda, MD, USA. .,Lyell Immunopharma, South San Francisco, CA, USA.
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3
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Targeting the MHC Ligandome by Use of TCR-Like Antibodies. Antibodies (Basel) 2019; 8:antib8020032. [PMID: 31544838 PMCID: PMC6640717 DOI: 10.3390/antib8020032] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2019] [Revised: 05/06/2019] [Accepted: 05/07/2019] [Indexed: 12/11/2022] Open
Abstract
Monoclonal antibodies (mAbs) are valuable as research reagents, in diagnosis and in therapy. Their high specificity, the ease in production, favorable biophysical properties and the opportunity to engineer different properties make mAbs a versatile class of biologics. mAbs targeting peptide–major histocompatibility molecule (pMHC) complexes are often referred to as “TCR-like” mAbs, as pMHC complexes are generally recognized by T-cell receptors (TCRs). Presentation of self- and non-self-derived peptide fragments on MHC molecules and subsequent activation of T cells dictate immune responses in health and disease. This includes responses to infectious agents or cancer but also aberrant responses against harmless self-peptides in autoimmune diseases. The ability of TCR-like mAbs to target specific peptides presented on MHC allows for their use to study peptide presentation or for diagnosis and therapy. This extends the scope of conventional mAbs, which are generally limited to cell-surface or soluble antigens. Herein, we review the strategies used to generate TCR-like mAbs and provide a structural comparison with the analogous TCR in pMHC binding. We further discuss their applications as research tools and therapeutic reagents in preclinical models as well as challenges and limitations associated with their use.
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Hickey JW, Vicente FP, Howard GP, Mao HQ, Schneck JP. Biologically Inspired Design of Nanoparticle Artificial Antigen-Presenting Cells for Immunomodulation. NANO LETTERS 2017; 17:7045-7054. [PMID: 28994285 PMCID: PMC6709596 DOI: 10.1021/acs.nanolett.7b03734] [Citation(s) in RCA: 96] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Particles engineered to engage and interact with cell surface ligands and to modulate cells can be harnessed to explore basic biological questions as well as to devise cellular therapies. Biology has inspired the design of these particles, such as artificial antigen-presenting cells (aAPCs) for use in immunotherapy. While much has been learned about mimicking antigen presenting cell biology, as we decrease the size of aAPCs to the nanometer scale, we need to extend biomimetic design to include considerations of T cell biology-including T-cell receptor (TCR) organization. Here we describe the first quantitative analysis of particle size effect on aAPCs with both Signals 1 and 2 based on T cell biology. We show that aAPCs, larger than 300 nm, activate T cells more efficiently than smaller aAPCs, 50 nm. The 50 nm aAPCs require saturating doses or require artificial magnetic clustering to activate T cells. Increasing ligand density alone on the 50 nm aAPCs did not increase their ability to stimulate CD8+ T cells, confirming the size-dependent phenomenon. These data support the need for multireceptor ligation and activation of T-cell receptor (TCR) nanoclusters of similar sizes to 300 nm aAPCs. Quantitative analysis and modeling of a nanoparticle system provides insight into engineering constraints of aAPCs for T cell immunotherapy applications and offers a case study for other cell-modulating particles.
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Affiliation(s)
- John W. Hickey
- Department of Biomedical Engineering, School of Medicine
- Institute for Cell Engineering, School of Medicine
- Translational Tissue Engineering Center
- Institute for Nanobiotechnology
| | | | - Gregory P. Howard
- Department of Biomedical Engineering, School of Medicine
- Institute for Nanobiotechnology
| | - Hai-Quan Mao
- Translational Tissue Engineering Center
- Institute for Nanobiotechnology
- Department of Materials Science and Engineering, Whiting School of Engineering
| | - Jonathan P. Schneck
- Institute for Cell Engineering, School of Medicine
- Department of Pathology, School of Medicine
- Institute for Nanobiotechnology
- Department of Medicine, School of Medicine, Johns Hopkins University, Baltimore, Maryland 21231, United States
- Corresponding Author: . Phone: 410-614-4589
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Huang J, Brameshuber M, Zeng X, Xie J, Li QJ, Chien YH, Valitutti S, Davis MM. A single peptide-major histocompatibility complex ligand triggers digital cytokine secretion in CD4(+) T cells. Immunity 2013; 39:846-57. [PMID: 24120362 PMCID: PMC3846396 DOI: 10.1016/j.immuni.2013.08.036] [Citation(s) in RCA: 251] [Impact Index Per Article: 22.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2012] [Accepted: 08/02/2013] [Indexed: 11/26/2022]
Abstract
We have developed a single-molecule imaging technique that uses quantum-dot-labeled peptide-major histocompatibility complex (pMHC) ligands to study CD4(+) T cell functional sensitivity. We found that naive T cells, T cell blasts, and memory T cells could all be triggered by a single pMHC to secrete tumor necrosis factor-α (TNF-α) and interleukin-2 (IL-2) cytokines with a rate of ∼1,000, ∼10,000, and ∼10,000 molecules/min, respectively, and that additional pMHCs did not augment secretion, indicating a digital response pattern. We also found that a single pMHC localized to the immunological synapse induced the slow formation of a long-lasting T cell receptor (TCR) cluster, consistent with a serial engagement mechanism. These data show that scaling up CD4(+) T cell cytokine responses involves increasingly efficient T cell recruitment rather than greater cytokine production per cell.
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Affiliation(s)
- Jun Huang
- Department of Microbiology and Immunology, Stanford University, Stanford, CA 94305, USA
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Misumi I, Alirezaei M, Eam B, Su MA, Whitton JL, Whitmire JK. Differential T cell responses to residual viral antigen prolong CD4+ T cell contraction following the resolution of infection. THE JOURNAL OF IMMUNOLOGY 2013; 191:5655-68. [PMID: 24146043 DOI: 10.4049/jimmunol.1301215] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The contraction phase of the T cell response is a poorly understood period after the resolution of infection when virus-specific effector cells decline in number and memory cells emerge with increased frequencies. CD8(+) T cells plummet in number and quickly reach stable levels of memory following acute lymphocytic choriomeningitis virus infection in mice. In contrast, virus-specific CD4(+) T cells gradually decrease in number and reach homeostatic levels only after many weeks. In this study, we provide evidence that MHCII-restricted viral Ag persists during the contraction phase following this prototypical acute virus infection. We evaluated whether the residual Ag affected the cell division and number of virus-specific naive and memory CD4(+) T cells and CD8(+) T cells. We found that naive CD4(+) T cells underwent cell division and accumulated in response to residual viral Ag for >2 mo after the eradication of infectious virus. Surprisingly, memory CD4(+) T cells did not undergo cell division in response to the lingering Ag, despite their heightened capacity to recognize Ag and make cytokine. In contrast to CD4(+) T cells, CD8(+) T cells did not undergo cell division in response to the residual Ag. Thus, CD8(+) T cells ceased division within days after the infection was resolved, indicating that CD8(+) T cell responses are tightly linked to endogenous processing of de novo synthesized virus protein. Our data suggest that residual viral Ag delays the contraction of CD4(+) T cell responses by recruiting new populations of CD4(+) T cells.
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Affiliation(s)
- Ichiro Misumi
- Department of Genetics, University of North Carolina School of Medicine, Chapel Hill, NC 27599
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Salles A, Billaudeau C, Sergé A, Bernard AM, Phélipot MC, Bertaux N, Fallet M, Grenot P, Marguet D, He HT, Hamon Y. Barcoding T cell calcium response diversity with methods for automated and accurate analysis of cell signals (MAAACS). PLoS Comput Biol 2013; 9:e1003245. [PMID: 24086124 PMCID: PMC3784497 DOI: 10.1371/journal.pcbi.1003245] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2013] [Accepted: 08/15/2013] [Indexed: 01/24/2023] Open
Abstract
We introduce a series of experimental procedures enabling sensitive calcium monitoring in T cell populations by confocal video-microscopy. Tracking and post-acquisition analysis was performed using Methods for Automated and Accurate Analysis of Cell Signals (MAAACS), a fully customized program that associates a high throughput tracking algorithm, an intuitive reconnection routine and a statistical platform to provide, at a glance, the calcium barcode of a population of individual T-cells. Combined with a sensitive calcium probe, this method allowed us to unravel the heterogeneity in shape and intensity of the calcium response in T cell populations and especially in naive T cells, which display intracellular calcium oscillations upon stimulation by antigen presenting cells. The adaptive immune response to pathogen invasion requires the stimulation of lymphocytes by antigen-presenting cells. We hypothesized that investigating the dynamics of the T lymphocyte activation by monitoring intracellular calcium fluctuations might help explain the high specificity and selectivity of this phenomenon. However, the quantitative and exhaustive analysis of calcium fluctuations by video microscopy in the context of cell-to-cell contact is a tough challenge. To tackle this, we developed a complete solution named MAAACS (Methods for Automated and Accurate Analysis of Cell Signals), in order to automate the detection, cell tracking, raw data ordering and analysis of calcium signals. Our algorithm revealed that, when in contact with antigen-presenting cells, T lymphocytes generate oscillating calcium signals and not a massive and sustained calcium response as was originally thought. We anticipate our approach providing many more new insights into the molecular mechanisms triggering adaptive immunity.
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Affiliation(s)
- Audrey Salles
- Centre d'Immunologie de Marseille-Luminy (CIML), Aix-Marseille University, UM2, Marseille, France
- Institut National de la Santé et de la Recherche Médicale (Inserm), U1104, Marseille, France
- Centre National de la Recherche Scientifique (CNRS) UMR7280, Marseille, France
| | - Cyrille Billaudeau
- Centre d'Immunologie de Marseille-Luminy (CIML), Aix-Marseille University, UM2, Marseille, France
- Institut National de la Santé et de la Recherche Médicale (Inserm), U1104, Marseille, France
- Centre National de la Recherche Scientifique (CNRS) UMR7280, Marseille, France
| | - Arnauld Sergé
- Centre d'Immunologie de Marseille-Luminy (CIML), Aix-Marseille University, UM2, Marseille, France
- Institut National de la Santé et de la Recherche Médicale (Inserm), U1104, Marseille, France
- Centre National de la Recherche Scientifique (CNRS) UMR7280, Marseille, France
- * E-mail: (AS); (YH)
| | - Anne-Marie Bernard
- Centre d'Immunologie de Marseille-Luminy (CIML), Aix-Marseille University, UM2, Marseille, France
- Institut National de la Santé et de la Recherche Médicale (Inserm), U1104, Marseille, France
- Centre National de la Recherche Scientifique (CNRS) UMR7280, Marseille, France
| | - Marie-Claire Phélipot
- Centre d'Immunologie de Marseille-Luminy (CIML), Aix-Marseille University, UM2, Marseille, France
- Institut National de la Santé et de la Recherche Médicale (Inserm), U1104, Marseille, France
- Centre National de la Recherche Scientifique (CNRS) UMR7280, Marseille, France
| | - Nicolas Bertaux
- Institut Fresnel, Centre National de la Recherche Scientifique (CNRS) UMR7249, Marseille, France
- École Centrale Marseille, Technopôle de Château-Gombert, Marseille, France
| | - Mathieu Fallet
- Centre d'Immunologie de Marseille-Luminy (CIML), Aix-Marseille University, UM2, Marseille, France
- Institut National de la Santé et de la Recherche Médicale (Inserm), U1104, Marseille, France
- Centre National de la Recherche Scientifique (CNRS) UMR7280, Marseille, France
| | - Pierre Grenot
- Centre d'Immunologie de Marseille-Luminy (CIML), Aix-Marseille University, UM2, Marseille, France
- Institut National de la Santé et de la Recherche Médicale (Inserm), U1104, Marseille, France
- Centre National de la Recherche Scientifique (CNRS) UMR7280, Marseille, France
| | - Didier Marguet
- Centre d'Immunologie de Marseille-Luminy (CIML), Aix-Marseille University, UM2, Marseille, France
- Institut National de la Santé et de la Recherche Médicale (Inserm), U1104, Marseille, France
- Centre National de la Recherche Scientifique (CNRS) UMR7280, Marseille, France
| | - Hai-Tao He
- Centre d'Immunologie de Marseille-Luminy (CIML), Aix-Marseille University, UM2, Marseille, France
- Institut National de la Santé et de la Recherche Médicale (Inserm), U1104, Marseille, France
- Centre National de la Recherche Scientifique (CNRS) UMR7280, Marseille, France
| | - Yannick Hamon
- Centre d'Immunologie de Marseille-Luminy (CIML), Aix-Marseille University, UM2, Marseille, France
- Institut National de la Santé et de la Recherche Médicale (Inserm), U1104, Marseille, France
- Centre National de la Recherche Scientifique (CNRS) UMR7280, Marseille, France
- * E-mail: (AS); (YH)
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Bosch B, Heipertz EL, Drake JR, Roche PA. Major histocompatibility complex (MHC) class II-peptide complexes arrive at the plasma membrane in cholesterol-rich microclusters. J Biol Chem 2013; 288:13236-42. [PMID: 23532855 DOI: 10.1074/jbc.m112.442640] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
BACKGROUND Antigen-specific CD4 T cells are activated by small numbers of antigenic peptide-MHC class II (pMHC-II) complexes on dendritic cells (DCs). RESULTS Newly generated pMHC-II complexes are present in small clusters on the DC surface. CONCLUSION pMHC-II clusters permit efficient T cell activation. SIGNIFICANCE The appearance of clustered pMHC-II reveals the organization of the T cell antigen receptor ligand on the DC surface. Dendritic cells (DCs) function by stimulating naive antigen-specific CD4 T cells to proliferate and secrete a variety of immunomodulatory factors. The ability to activate naive T cells comes from the capacity of DCs to internalize, degrade, and express peptide fragments of antigenic proteins on their surface bound to MHC class II molecules (MHC-II). Although DCs express tens of thousands of distinct MHC-II, very small amounts of specific peptide-MHC-II complexes are required to interact with and activate T cells. We now show that stimulatory MHC-II I-A(k)-HEL(46-61) complexes that move from intracellular antigen-processing compartments to the plasma membrane are not randomly distributed on the DC surface. Confocal immunofluorescence microscopy and quantitative immunoelectron microscopy reveal that the majority of newly generated MHC-II I-A(k)-HEL(46-61) complexes are expressed in sub-100-nm microclusters on the DC membrane. These microclusters are stabilized in cholesterol-containing microdomains, and cholesterol depletion inhibits the stability of these clusters as well as the ability of the DCs to function as antigen-presenting cells. These results demonstrate that specific cohorts of peptide-MHC-II complexes expressed on the DC surface are present in cholesterol-dependent microclusters and that cluster integrity is important for antigen-specific naive CD4 T cell activation by DCs.
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Affiliation(s)
- Berta Bosch
- Experimental Immunology Branch, NCI, National Institutes of Health, Bethesda, MD 20892, USA
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Yokosuka T, Takamatsu M, Kobayashi-Imanishi W, Hashimoto-Tane A, Azuma M, Saito T. Programmed cell death 1 forms negative costimulatory microclusters that directly inhibit T cell receptor signaling by recruiting phosphatase SHP2. ACTA ACUST UNITED AC 2012; 209:1201-17. [PMID: 22641383 PMCID: PMC3371732 DOI: 10.1084/jem.20112741] [Citation(s) in RCA: 778] [Impact Index Per Article: 64.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
After encounter with its ligand, PD-1 translocates into TCR microclusters, where it transiently recruits SHP2 and suppresses phosphorylation of TCR signaling components and TCR-driven stop signals. Programmed cell death 1 (PD-1) is a negative costimulatory receptor critical for the suppression of T cell activation in vitro and in vivo. Single cell imaging elucidated a molecular mechanism of PD-1–mediated suppression. PD-1 becomes clustered with T cell receptors (TCRs) upon binding to its ligand PD-L1 and is transiently associated with the phosphatase SHP2 (Src homology 2 domain–containing tyrosine phosphatase 2). These negative costimulatory microclusters induce the dephosphorylation of the proximal TCR signaling molecules. This results in the suppression of T cell activation and blockade of the TCR-induced stop signal. In addition to PD-1 clustering, PD-1–TCR colocalization within microclusters is required for efficient PD-1–mediated suppression. This inhibitory mechanism also functions in PD-1hi T cells generated in vivo and can be overridden by a neutralizing anti–PD-L1 antibody. Therefore, PD-1 microcluster formation is important for regulation of T cell activation.
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Affiliation(s)
- Tadashi Yokosuka
- Laboratory for Cell Signaling, RIKEN Research Center for Allergy and Immunology, Yokohama, Kanagawa 230-0045, Japan.
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Abstract
Signaling processes between various immune cells involve large-scale spatial reorganization of receptors and signaling molecules within the cell-cell junction. These structures, now collectively referred to as immune synapses, interleave physical and mechanical processes with the cascades of chemical reactions that constitute signal transduction systems. Molecular level clustering, spatial exclusion, and long-range directed transport are all emerging as key regulatory mechanisms. The study of these processes is drawing researchers from physical sciences to join the effort and represents a rapidly growing branch of biophysical chemistry. Recent advances in physical and quantitative analyses of signaling within the immune synapses are reviewed here.
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Affiliation(s)
- Michael L Dustin
- Program in Molecular Pathogenesis, Skirball Institute of Biomolecular Medicine and Department of Pathology, New York University School of Medicine, New York, New York 10016, USA.
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Manz BN, Jackson BL, Petit RS, Dustin ML, Groves J. T-cell triggering thresholds are modulated by the number of antigen within individual T-cell receptor clusters. Proc Natl Acad Sci U S A 2011; 108:9089-94. [PMID: 21576490 PMCID: PMC3107331 DOI: 10.1073/pnas.1018771108] [Citation(s) in RCA: 149] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
T cells react to extremely small numbers of activating agonist peptides. Spatial organization of T-cell receptors (TCR) and their peptide-major histocompatibility complex (pMHC) ligands into microclusters is correlated with T-cell activation. Here we have designed an experimental strategy that enables control over the number of agonist peptides per TCR cluster, without altering the total number engaged by the cell. Supported membranes, partitioned with grids of barriers to lateral mobility, provide an effective way of limiting the total number of pMHC ligands that may be assembled within a single TCR cluster. Observations directly reveal that restriction of pMHC content within individual TCR clusters can decrease T-cell sensitivity for triggering initial calcium flux at fixed total pMHC density. Further analysis suggests that triggering thresholds are determined by the number of activating ligands available to individual TCR clusters, not by the total number encountered by the cell. Results from a series of experiments in which the overall agonist density and the maximum number of agonist per TCR cluster are independently varied in primary T cells indicate that the most probable minimal triggering unit for calcium signaling is at least four pMHC in a single cluster for this system. This threshold is unchanged by inclusion of coagonist pMHC, but costimulation of CD28 by CD80 can modulate the threshold lower.
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Affiliation(s)
- Boryana N. Manz
- Howard Hughes Medical Institute, Department of Chemistry, and
- Biophysics Graduate Group, University of California, Berkeley, CA 94720
| | - Bryan L. Jackson
- Howard Hughes Medical Institute, Department of Chemistry, and
- Physical Biosciences and Materials Sciences Divisions, Lawrence Berkeley National Laboratory, Berkeley, CA 94720; and
| | - Rebecca S. Petit
- Howard Hughes Medical Institute, Department of Chemistry, and
- Physical Biosciences and Materials Sciences Divisions, Lawrence Berkeley National Laboratory, Berkeley, CA 94720; and
| | - Michael L. Dustin
- Program in Molecular Pathogenesis, Skirball Institute of Biomolecular Medicine and Department of Pathology, New York University School of Medicine, New York, NY 10016
| | - Jay Groves
- Howard Hughes Medical Institute, Department of Chemistry, and
- Biophysics Graduate Group, University of California, Berkeley, CA 94720
- Physical Biosciences and Materials Sciences Divisions, Lawrence Berkeley National Laboratory, Berkeley, CA 94720; and
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Lunde E, Løset GÅ, Bogen B, Sandlie I. Stabilizing mutations increase secretion of functional soluble TCR-Ig fusion proteins. BMC Biotechnol 2010; 10:61. [PMID: 20735812 PMCID: PMC2936418 DOI: 10.1186/1472-6750-10-61] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2009] [Accepted: 08/24/2010] [Indexed: 12/02/2022] Open
Abstract
Background Whereas T cell receptors (TCRs) detect peptide/major histocompatibility complexes (pMHCs) with exquisite specificity, there are challenges regarding their expression and use as soluble detection molecules due to molecular instability. We have investigated strategies for the production of TCR-immunoglobulin (Ig) fusion proteins. Two different TCRs that are characteristic of a mouse model for idiotype (Id) dependent immune regulation were engineered. They are structurally unrelated with different variable (V), diversity (D) and joining (J) segments, but each share one V gene segment, either Vα or Vβ, with the well characterized murine TCR, 2C. Results Several TCR-Ig formats were assessed. In one, the TCR V domains were fused to Ig constant (C) regions. In others, the complete extracellular part of the TCR was fused either to a complete Ig or an Ig Fc region. All molecules were initially poorly secreted from eukaryotic cells, but replacement of unfavourable amino acids in the V regions improved secretion, as did the introduction of a disulfide bridge between the TCR C domains and the removal of an unpaired cysteine. A screening strategy for selection of mutations that stabilize the actual fusion molecules was developed and used successfully. Molecules that included the complete heterodimeric TCR, with a stabilizing disulfide bridge, were correctly folded as they bound TCR-specific antibodies (Abs) and detected pMHC on cells after specific peptide loading. Conclusions We show that fully functional TCR-Ig fusion proteins can be made in good yields following stabilizing engineering of TCR V and C region genes. This is important since TCR-Ig fusions will be important probes for the presence of specific pMHCs in vitro and in vivo. In the absence of further affinity maturation, the reagents will be very useful for the detection of kinetic stability of complexes of peptide and MHC.
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Affiliation(s)
- Elin Lunde
- Department of Molecular Biosciences, Centre for Immune Regulation, University of Oslo, Oslo 0316, Norway
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Lowering TCR expression on naive CD8+ T cells does not affect memory T-cell differentiation. Immunol Cell Biol 2010; 89:322-5. [PMID: 20585337 DOI: 10.1038/icb.2010.80] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The generation of long-lived memory T (Tm) cells is critical for the success of vaccination, but the factors controlling their differentiation are still poorly defined. We examined the hypothesis that the level of T-cell receptor (TCR) engagement contributed to memory CD8(+) T-cell generation. By manipulating TCR expression levels on murine, naive ovalbumin (OVA)-specific CD8(+) T cells, we showed that the expansion of antigen (Ag)-specific CD8(+) T cells is minimally affected by the level of TCR expression. Indeed, naive CD8(+) T cells expressing as little as a 1000 TCRs (30-fold less) show only a 2.5-fold reduction in the number of effectors generated. Furthermore, the TCR expression levels influenced neither the acquisition of effector functions nor the generation of functional Tm cells. Our data indicate that during an in vivo immune response, a threshold in the number of TCRs engaged by naive CD8(+) T cells is required for full T-cell expansion but not for their differentiation into effector and Tm cells.
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Atibalentja DF, Byersdorfer CA, Unanue ER. Thymus-blood protein interactions are highly effective in negative selection and regulatory T cell induction. THE JOURNAL OF IMMUNOLOGY 2010; 183:7909-18. [PMID: 19933868 DOI: 10.4049/jimmunol.0902632] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Using hen egg-white lysozyme, the effect of blood proteins on CD4 thymic cells was examined. A small fraction of i.v. injected hen egg-white lysozyme rapidly entered the thymus into the medulla. There it was captured and presented by dendritic cells (DCs) to thymocytes from two TCR transgenic mice, one directed to a dominant peptide and a second to a poorly displayed peptide, both presented by MHC class II molecules I-A(k). Presentation by DC led to negative selection and induction of regulatory T cells, independent of epithelial cells. Presentation took place at very low levels, less than 100 peptide-MHC complexes per DC. Such low levels could induce negative selection, but even lower levels could induce regulatory T cells. The anatomy of the thymus-blood barrier, the highly efficient presentation by DC, together with the high sensitivity of thymic T cells to peptide-MHC complexes, results in blood protein Ags having a profound effect on thymic T cells.
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Affiliation(s)
- Danielle F Atibalentja
- Department of Pathology and Immunology, Washington University School of Medicine, St Louis, MO 63110, USA
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15
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Manipulating antigenic ligand strength to selectively target myelin-reactive CD4+ T cells in EAE. J Neuroimmune Pharmacol 2009; 5:176-88. [PMID: 19904613 DOI: 10.1007/s11481-009-9181-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2009] [Accepted: 10/15/2009] [Indexed: 10/20/2022]
Abstract
The development of antigen-specific therapies for the selective tolerization of autoreactive T cells remains the Holy Grail for the treatment of T-cell-mediated autoimmune diseases such as multiple sclerosis (MS) and its animal model experimental autoimmune encephalomyelitis (EAE). This quest remains elusive, however, as the numerous antigen-specific strategies targeting myelin-specific T cells over the years have failed to result in clinical success. In this review, we revisit the antigen-based therapies used in the treatment of myelin-specific CD4+ T cells in the context of the functional avidity and the strength of signal of the encephalitogenic CD4+ T cell repertoire. In light of differences in activation thresholds, we propose that autoreactive T cells are not all equal, and therefore tolerance induction strategies must incorporate ligand strength in order to be successful in treating EAE and ultimately the human disease MS.
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16
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Lazaro E, Godfrey SB, Stamegna P, Ogbechie T, Kerrigan C, Zhang M, Walker BD, Le Gall S. Differential HIV epitope processing in monocytes and CD4 T cells affects cytotoxic T lymphocyte recognition. J Infect Dis 2009; 200:236-43. [PMID: 19505257 PMCID: PMC3724235 DOI: 10.1086/599837] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
The ability of cytotoxic T lymphocytes (CTLs) to clear virus-infected cells is dependent on the presentation of viral peptides processed intracellularly and displayed by major histocompatibility complex class I. Most CTL functional assays use exogenously added peptides, a practice that does not account for the kinetics and quantity of antigenic peptides produced by infectable cells. Here, we examined the relative ability of 2 major human immunodeficiency virus-infectable cell subsets-CD4 T lymphocytes and monocytes-to produce antigenic peptides, using cytosol as a source of peptidases and mass spectrometry to define the degradation products. We show clear subset-specific differences in the kinetics of peptide production and the ability of the peptides produced to sensitize cells for lysis by CTLs, with primary CD4 T lymphocytes having significantly lower proteolytic activity than monocytes. These differences in epitope processing by cell subsets may affect the efficiency of CTL-mediated clearance of infected subsets and contribute to the establishment of chronic infection.
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Affiliation(s)
- Estibaliz Lazaro
- Ragon Institute of MGH, MIT and Harvard (formerly Partners AIDS Research Center), Massachusetts General Hospital, Harvard Medical School, CNY 149 13 street, Boston, MA 02129
| | - Sasha Blue Godfrey
- Ragon Institute of MGH, MIT and Harvard (formerly Partners AIDS Research Center), Massachusetts General Hospital, Harvard Medical School, CNY 149 13 street, Boston, MA 02129
| | - Pamela Stamegna
- Ragon Institute of MGH, MIT and Harvard (formerly Partners AIDS Research Center), Massachusetts General Hospital, Harvard Medical School, CNY 149 13 street, Boston, MA 02129
| | - Tobi Ogbechie
- Ragon Institute of MGH, MIT and Harvard (formerly Partners AIDS Research Center), Massachusetts General Hospital, Harvard Medical School, CNY 149 13 street, Boston, MA 02129
| | - Christopher Kerrigan
- Ragon Institute of MGH, MIT and Harvard (formerly Partners AIDS Research Center), Massachusetts General Hospital, Harvard Medical School, CNY 149 13 street, Boston, MA 02129
| | - Mei Zhang
- Ragon Institute of MGH, MIT and Harvard (formerly Partners AIDS Research Center), Massachusetts General Hospital, Harvard Medical School, CNY 149 13 street, Boston, MA 02129
| | - Bruce D. Walker
- Ragon Institute of MGH, MIT and Harvard (formerly Partners AIDS Research Center), Massachusetts General Hospital, Harvard Medical School, CNY 149 13 street, Boston, MA 02129
- Howard Hughes Medical Institute, 4000 Jones Bridge Road, Chevy Chase, MD 20815-6789
| | - Sylvie Le Gall
- Ragon Institute of MGH, MIT and Harvard (formerly Partners AIDS Research Center), Massachusetts General Hospital, Harvard Medical School, CNY 149 13 street, Boston, MA 02129
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17
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Beal AM, Anikeeva N, Varma R, Cameron TO, Norris PJ, Dustin ML, Sykulev Y. Protein kinase C theta regulates stability of the peripheral adhesion ring junction and contributes to the sensitivity of target cell lysis by CTL. THE JOURNAL OF IMMUNOLOGY 2008; 181:4815-24. [PMID: 18802085 DOI: 10.4049/jimmunol.181.7.4815] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Destruction of virus-infected cells by CTL is an extremely sensitive and efficient process. Our previous data suggest that LFA-1-ICAM-1 interactions in the peripheral supramolecular activation cluster (pSMAC) of the immunological synapse mediate formation of a tight adhesion junction that might contribute to the sensitivity of target cell lysis by CTL. Herein, we compared more (CD8(+)) and less (CD4(+)) effective CTL to understand the molecular events that promote efficient target cell lysis. We found that abrogation of the pSMAC formation significantly impaired the ability of CD8(+) but not CD4(+) CTL to lyse target cells despite having no effect of the amount of released granules by both CD8(+) and CD4(+) CTL. Consistent with this, CD4(+) CTL break their synapses more often than do CD8(+) CTL, which leads to the escape of the cytolytic molecules from the interface. CD4(+) CTL treatment with a protein kinase Ctheta inhibitor increases synapse stability and sensitivity of specific target cell lysis. Thus, formation of a stable pSMAC, which is partially controlled by protein kinase Ctheta, functions to confine the released lytic molecules at the synaptic interface and to enhance the effectiveness of target cell lysis.
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Affiliation(s)
- Allison M Beal
- Department of Microbiology and Immunology and Kimmel Cancer Institute, Thomas Jefferson University, Philadelphia, PA 19107, USA
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18
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Mareeva T, Martinez-Hackert E, Sykulev Y. How a T cell receptor-like antibody recognizes major histocompatibility complex-bound peptide. J Biol Chem 2008; 283:29053-9. [PMID: 18703505 PMCID: PMC2570882 DOI: 10.1074/jbc.m804996200] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2008] [Revised: 07/30/2008] [Indexed: 11/06/2022] Open
Abstract
We determined the crystal structures of the T cell receptor (TCR)-like antibody 25-D1.16 Fab fragment bound to a complex of SIINFEKL peptide from ovalbumin and the H-2K(b) molecule. Remarkably, this antibody directly "reads" the structure of the major histocompatibility complex (MHC)-bound peptide, employing the canonical diagonal binding mode utilized by most TCRs. This is in marked contrast with another TCR-like antibody, Hyb3, bound to melanoma peptide MAGE-A1 in association with HLA-A1 MHC class I. Hyb3 assumes a non-canonical orientation over its cognate peptide-MHC and appears to recognize a conformational epitope in which the MHC contribution is dominant. We conclude that TCR-like antibodies can recognize MHC-bound peptide via two different mechanisms: one is similar to that exploited by the preponderance of TCRs and the other requires a non-canonical antibody orientation over the peptide-MHC complex.
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Affiliation(s)
- Tatiana Mareeva
- Department of Microbiology and Immunology and the Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA
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19
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Abstract
The interaction between the T cell receptor (TCR) and a peptide-loaded major histocompatibility complex (pMHC) is one of the most-studied interactions in immunology, and yet the precise mechanism by which this system operates is still not fully understood. One key issue is whether TCR triggering minimally requires monomeric pMHC complexes or higher-order multimers (two or more pMHCs). Any model of TCR triggering must explain the high sensitivity, specificity, and dynamic range of ligand responsiveness that this receptor system exhibits. Most models of TCR triggering have not fully appreciated the dynamic aspects of TCR triggering. TCR triggering happens very quickly, and the properties of sensitivity and specificity can be explained by a model that accounts for the interaction dynamics of such a receptor system. In this paper, it is proposed that the important parameter in TCR triggering is the immobilization of the TCR-pMHC complex in the plasma membrane. Whether this involves monomeric or multimeric pMHCs may depend on the affinity of the TCR for the pMHC.
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Affiliation(s)
- Rajat Varma
- Laboratory of Cellular and Molecular Immunology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 4 Center Drive, Bethesda, MD 20892, USA.
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20
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DeMond AL, Groves JT. Interrogating the T cell synapse with patterned surfaces and photoactivated proteins. Curr Opin Immunol 2007; 19:722-7. [PMID: 17703931 DOI: 10.1016/j.coi.2007.07.008] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2007] [Revised: 06/06/2007] [Accepted: 07/04/2007] [Indexed: 10/22/2022]
Abstract
The immunological synapse is a site rich in spatially modulated signaling cascades. The importance of spatial organization in intercellular signal transduction has prompted much recent interest in techniques to control the localization of cell-surface signaling molecules to investigate synaptic signaling. Photoactivation, patterning, and mechanical constraint of surface-associated molecules are three prominent examples of such techniques. Recent results have demonstrated the effectiveness of these techniques as tools to investigate the mechanisms of immune synapse assembly and synaptic signaling.
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21
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Løset GÅ, Lunde E, Bogen B, Brekke OH, Sandlie I. Functional phage display of two murine alpha/beta T-cell receptors is strongly dependent on fusion format, mode and periplasmic folding assistance. Protein Eng Des Sel 2007; 20:461-72. [PMID: 17925331 DOI: 10.1093/protein/gzm044] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Phage display has been instrumental for the success of antibody (Ab) technology. The aim of the present study was to explore phage display of soluble T-cell receptors (TCRs). A library platform that supports engineering and selection of improved TCRs to be used as detection reagents for specific antigen presentation will be very useful. In such applications, high, equal and clone independent display levels are a prerequisite for 'fair' selection. Therefore, we explored how different pIII fusion formats and modes affected the display levels of two murine alpha/beta TCRs. Both are derived from T-cell clones associated with the MOPC315 myeloma model. The results show that the design of the pIII fusion particle significantly affects the subsequent display levels. Furthermore, successful display may be obtained both in phagemid and phage versions. Importantly, improvement of poor display can be achieved by over-expressing the periplasmic chaperone FkpA.
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Affiliation(s)
- G Å Løset
- Department of Molecular Biosciences, University of Oslo, N-0316 Oslo, Norway.
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22
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Abstract
In light of recent data showing that both helper and cytotoxic T cells can detect even a single molecule of an agonist peptide-MHC, alphabeta T cells are clearly a type of sensory cell, comparable to any in the nervous system. In addition, endogenous (self) peptides bound to MHCs are not just important for thymic selection, but also play an integral role in T cell activation in the response to foreign antigens. With the multitude of specificities available to most T cells, they can thus be considered as a sensory organ, trained on self-peptide-MHCs and primed to detect nonself.
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Affiliation(s)
- Mark M Davis
- Howard Hughes Medical Institute, Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, California 94305, USA.
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23
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Krogsgaard M, Juang J, Davis MM. A role for "self" in T-cell activation. Semin Immunol 2007; 19:236-44. [PMID: 17548210 PMCID: PMC2731063 DOI: 10.1016/j.smim.2007.04.003] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/27/2007] [Revised: 04/16/2007] [Accepted: 04/17/2007] [Indexed: 11/24/2022]
Abstract
The mechanisms by which alphabeta T-cells are selected in the thymus and then recognize peptide MHC (pMHC) complexes in the periphery remain an enigma. Recent work particularly with respect to quantification of T-cell sensitivity and the role of self-ligands in T-cell activation has provided some important clues to the details of how TCR signaling might be initiated. Here, we highlight recent experimental data that provides insights into the initiation of T-cell activation and also discuss the main controversies and uncertainties in this area.
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Affiliation(s)
- Michelle Krogsgaard
- Department of Pathology and NYU Cancer Institute, NYU School of Medicine, New York, NY 10016, USA.
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24
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Shishkova Y, Harms H, Krohne G, Avota E, Schneider-Schaulies S. Immune synapses formed with measles virus-infected dendritic cells are unstable and fail to sustain T cell activation. Cell Microbiol 2007; 9:1974-86. [PMID: 17394561 DOI: 10.1111/j.1462-5822.2007.00928.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Interaction with dendritic cells (DCs) is considered as central to immunosuppression induced by viruses, including measles virus (MV). Commonly, viral infection of DCs abrogates their ability to promote T cell expansion, yet underlying mechanisms at a cellular level are undefined. We found that MV-infected DCs only subtly differed from LPS-matured with regard to integrin activation, acquisition of a migratory phenotype and motility. Similarly, the organization of MV-DC/T cell interfaces was consistent with that of functional immune synapses with regard to CD3 clustering and MHC class II surface recruitment. The majority of MV-DC/T cell conjugates was, however, unstable and only promoted abortive T cell activation. Thus, MV-infected DCs retain activities required for initiating, but not sustaining T cell conjugation and activation. This is partially rescued if surface expression of the MV glycoproteins on DCs is abolished by infection with a recombinant MV encoding VSV G protein instead, indicating that these contribute directly to synapse destabilization and thereby act as effectors of T cell inhibition.
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Affiliation(s)
- Yoanna Shishkova
- University of Würzburg, Institute for Virology and Immunobiology, Versbacher Street 7, D-97078 Würzburg, Germany
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25
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Wolk K, Höflich C, Zuckermann-Becker H, Döcke WD, Volk HD, Sabat R. Reduced monocyte CD86 expression in postinflammatory immunodeficiency. Crit Care Med 2007; 35:458-67. [PMID: 17204999 DOI: 10.1097/01.ccm.0000254724.54515.2f] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
OBJECTIVE Major surgery, polytrauma, stroke, and pancreatitis frequently lead to a compensatory anti-inflammatory response syndrome that often predisposes patients to lethal infections. This temporary postinflammatory immunodeficiency is characterized by altered function of blood monocytes. These cells show strongly reduced inflammatory and antigen-presentation capacity. Diminished monocyte expression of the major histocompatibility complex class II molecule human leukocyte antigen (HLA)-DR is a well-established diagnostic marker of this immunodeficiency. To further characterize the monocytic cells in this clinical state, we analyzed their expression of CD86, the most important co-stimulatory molecule. DESIGN Analysis of blood samples that entered the clinical immunologic diagnostics and of cells from an in vitro model of postinflammatory immunodeficiency. SETTING University laboratory. SUBJECTS Healthy donors and intensive care unit (ICU) patients at the university hospital. INTERVENTIONS None. MEASUREMENTS AND MAIN RESULTS The expression of HLA-DR on monocytes and of CD86 and CD80 on monocytes and B cells was analyzed by flow cytometry. Messenger RNA expression of CD86 was analyzed in isolated monocytes by real-time polymerase chain reaction on reverse transcribed. The normal range of monocyte CD86 expression in healthy subjects was established to be from 2128 to 5102 surface molecules per cell and was independent of age, gender, and leukocyte and monocyte count. The CD86 expression on monocytes in ICU patients correlated with HLA-DR expression. Approximately 40% of the ICU patients with long-term reduced monocyte HLA-DR expression had a long-term reduction of CD86 expression. Patients in whom the expression of both molecules was diminished had an unfavorable prognosis. The diminished number of CD86 surface molecules on monocytes was associated with reduced CD86 messenger RNA levels in these cells. The expression of CD86 in B cells was not diminished in immunodeficient patients. The expression of CD80 in both monocytes and B-cells was minimal in healthy donors and not clearly changed in patients. CONCLUSIONS The monocyte CD86 expression may be a helpful diagnostic variable in ICU patients.
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Affiliation(s)
- Kerstin Wolk
- Institute of Medical Immunology and Department of General, Visceral, Vascular, Thoracic Surgery, University Hospital Charité, Berlin, Germany
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26
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Varma R, Campi G, Yokosuka T, Saito T, Dustin ML. T cell receptor-proximal signals are sustained in peripheral microclusters and terminated in the central supramolecular activation cluster. Immunity 2006; 25:117-27. [PMID: 16860761 PMCID: PMC1626533 DOI: 10.1016/j.immuni.2006.04.010] [Citation(s) in RCA: 665] [Impact Index Per Article: 36.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2005] [Revised: 01/04/2006] [Accepted: 04/12/2006] [Indexed: 12/11/2022]
Abstract
T cell receptor (TCR) signaling is initiated and sustained in microclusters; however, it's not known whether signaling also occurs in the TCR-rich central supramolecular activation cluster (cSMAC). We showed that the cSMAC formed by fusion of microclusters contained more CD45 than microclusters and is a site enriched in lysobisphosphatidic acid, a lipid involved in sorting ubiquitinated membrane proteins for degradation. Calcium signaling via TCR was blocked within 2 min by anti-MHCp treatment and 1 min by latrunculin-A treatment. TCR-MHCp interactions in the cSMAC survived these perturbations for 10 min and hence were not sufficient to sustain signaling. TCR microclusters were also resistant to disruption by anti-MHCp and latrunculin-A treatments. We propose that TCR signaling is sustained by stabilized microclusters and is terminated in the cSMAC, a structure from which TCR are sorted for degradation. Our studies reveal a role for F-actin in TCR signaling beyond microcluster formation.
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Affiliation(s)
- Rajat Varma
- Program in Molecular Pathogenesis, Skirball Institute of Biomolecular Medicine, Department of Pathology, New York University School of Medicine, 540 First Avenue, New York, New York 10016, USA
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27
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Joncker NT, Helft J, Jacquet A, Premel V, Lantz O. Intratumor CD4 T-Cell Accumulation Requires Stronger Priming than for Expansion and Lymphokine Secretion. Cancer Res 2006; 66:5443-51. [PMID: 16707473 DOI: 10.1158/0008-5472.can-05-3526] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
T cells need to migrate to and accumulate inside tumors before mediating rejection of the tumor. The number of specific T cells inside tumors may depend on the efficiency of priming in the draining lymph node (DLN), intratumor deletion, suppressive phenomena, or both. We used monoclonal anti-male antigen CD4 (Marilyn) T cells and tumor cell lines expressing or not the corresponding antigen (Dby) to analyze CD4 T-cell accumulation in tumors. Priming by MHC II(+) or MHC II(-) male splenocytes or Dby(+) tumor cells induced similar Marilyn T-cell expansion in the DLN and recirculation in other lymph nodes and capacity to produce IFN-gamma. However, intratumor accumulation was different for each priming condition. In mice with Dby(-) tumors, MHC II(+) male splenocyte priming induced greater, although not statistically significant, Marilyn T-cell accumulation in the tumors than MHC II(-) male splenocyte priming. In mice with Dby(+) tumors, priming in the tumor DLN induced less Marilyn T-cell intratumor accumulation than priming by MHC II(+) male splenocytes. We saw comparable differences for Marilyn T-cell accumulation in gut lamina propria, suggesting that priming affects effector T-cell accumulation in inflamed tissues. Mature dendritic cells were loaded with graded doses of Dby peptide to control for antigen-presenting cell characteristics during priming. We observed similar proliferation, with higher concentrations inducing higher intratumor accumulation. Thus, intratumor accumulation requires stronger stimulation than for proliferation or the capacity to secrete lymphokines. In this system, priming intensity alone can explain the number of intratumor T cells without having to call for intratumor deletion or suppression phenomena.
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Affiliation(s)
- Nathalie T Joncker
- Laboratoire d'Immunologie pré-clinique, Institut National de la Sante et de la Recherche Medicale U653, Institut Curie, Paris, France
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28
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Schamel WWA, Risueño RM, Minguet S, Ortíz AR, Alarcón B. A conformation- and avidity-based proofreading mechanism for the TCR–CD3 complex. Trends Immunol 2006; 27:176-82. [PMID: 16527543 DOI: 10.1016/j.it.2006.02.005] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2005] [Revised: 01/24/2006] [Accepted: 02/16/2006] [Indexed: 10/24/2022]
Abstract
During antigen recognition, T cells show high sensitivity and specificity, and a wide dynamic range. Paradoxically, these characteristics are based on low-affinity receptor-ligand interactions [between the T-cell antigen receptor (TCR-CD3) complex and the antigen peptide bound to MHC]. Recent evidence indicates that the TCR-CD3 is expressed as multivalent complexes in the membrane of non-stimulated T cells and that conformational changes in the TCR-CD3 can be induced by strong but not weak agonists. Here, we propose a thermodynamic model whereby the specificity of the TCR-CD3-pMHC interaction is explained by its multivalent nature. We also propose that the free energy barriers involved in the change in conformation of the receptor impose a response threshold and determine the kinetic properties of recognition. Finally, we suggest that multivalent TCR-CD3s can amplify signals by spreading them from pMHC-engaged TCR-CD3s to unengaged complexes as a consequence of the cooperativity in the system.
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Affiliation(s)
- Wolfgang W A Schamel
- Max Planck-Institut für Immunbiologie and University of Freiburg, Stübeweg 51, 79108 Freiburg, Germany
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29
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George AJT, Stark J, Chan C. Understanding specificity and sensitivity of T-cell recognition. Trends Immunol 2005; 26:653-9. [PMID: 16236548 DOI: 10.1016/j.it.2005.09.011] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2005] [Revised: 09/12/2005] [Accepted: 09/29/2005] [Indexed: 10/25/2022]
Abstract
The response of T cells to antigen shows an amazing degree of both sensitivity and specificity, with a cell responding to 1-10 peptide-MHC complexes and being sensitive to single amino acid substitutions. Kinetic proofreading or feedback pathways achieve specificity at the level of the receptor, whereas serial engagement of receptors by ligand molecules enhances sensitivity. Crosstalk between receptors, integration of signals and/or tuning of responses is important at the level of the cell. Induction of anergic or regulatory cells by suboptimal stimuli prevents cell activation by multiple encounters with weak ligands. Thus, for optimal sensitivity and specificity, it is necessary to have mechanisms that operate at the level of the receptor, the cell and finally, the population of responding cells.
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Affiliation(s)
- Andrew J T George
- Department of Immunology, Division of Medicine, Faculty of Medicine, Imperial College London, Hammersmith Campus, Du Cane Road, London, UK W12 0NN.
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30
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Bernardeau K, Gouard S, David G, Ruellan AL, Devys A, Barbet J, Bonneville M, Chérel M, Davodeau F. Assessment of CD8 involvement in T cell clone avidity by direct measurement of HLA-A2/Mage3 complex density using a high-affinity TCR like monoclonal antibody. Eur J Immunol 2005; 35:2864-75. [PMID: 16163672 DOI: 10.1002/eji.200526307] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Peptide affinity for MHC molecules determines the number of MHC/peptide complexes stabilized at the cell surface in in vitro tests or in vaccination protocols. We isolated a high affinity monoclonal antibody specific for the HLA-A2/Mage3 complex that enables an equilibrium binding assay to be performed on T2 cell line loaded with a range of Mage3 peptides. Binding of Mage3 to the HLA-A2 molecule can be modeled by a standard receptor-ligand interaction characterized by an affinity constant. This model enables the measurement of the affinity of other immunogenic peptides for HLA-A2 by a competition test and the calculation of the density of complexes stabilized at the T2 cell surface for all peptide concentrations. Quantification of the HLA-A2/Mage3 complexes at target cell surfaces was used to estimate the number of complexes required to reach cytotoxicity ED50 of human T cell clones sorted from an unprimed repertoire. We confirm with this antibody the direct relationship between clone avidity and TCR affinity, and the moderate contribution of the CD8 co-receptor in the reinforcement of TCR-MHC/peptide contact. Nevertheless, CD8 plays a critical role in the amplification of the specific signal to establish an efficient T cell response at low specific complex densities found in physiological situations.
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Affiliation(s)
- Karine Bernardeau
- INSERM U601, Institut de Biologie, and Université Nantes, Nantes, France
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31
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Garbi N, Tanaka S, van den Broek M, Momburg F, Hämmerling GJ. Accessory molecules in the assembly of major histocompatibility complex class I/peptide complexes: how essential are they for CD8+ T-cell immune responses? Immunol Rev 2005; 207:77-88. [PMID: 16181328 DOI: 10.1111/j.0105-2896.2005.00303.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Assembly of major histocompatibility complex (MHC) class I molecules in the endoplasmic reticulum is a highly coordinated process that results in abundant class I/peptide complexes at the cell surface for recognition by CD8(+) T cells and natural killer cells. During the assembly process, a number of chaperones and accessory molecules, such as transporter associated with antigen processing, tapasin, ER60, and calreticulin, assist newly synthesized class I molecules to facilitate loading of antigenic peptides and to optimize the repertoire of surface class I/peptide complexes. This review focuses on the relative importance of these accessory molecules for CD8(+) T-cell responses in vivo and discusses reasons that may help explain why some CD8(+) T-cell responses develop normally in mice deficient in components of class I assembly, despite impaired antigen presentation.
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Affiliation(s)
- Natalio Garbi
- Division of Molecular Immunology, German Cancer Research Center, Heidelberg, Germany
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32
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Abstract
Accumulating experimental evidence of stochasticity, self-organization and abrupt non-linear transitions underlying the dynamics of cellular structure and function is increasingly more consistent with the concepts and models of phase transitions, critical phenomena and non-linear thermodynamics rather than with the conventional clockwork description of the cell. The novel emerging image of the stochastic cell suggests that familiar and convenient classico-mechanical interpretations may be limiting our ability to understand the behavior of biological systems and calls for active exploration of alternative interpretational frameworks.
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33
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Schamel WWA, Arechaga I, Risueño RM, van Santen HM, Cabezas P, Risco C, Valpuesta JM, Alarcón B. Coexistence of multivalent and monovalent TCRs explains high sensitivity and wide range of response. ACTA ACUST UNITED AC 2005; 202:493-503. [PMID: 16087711 PMCID: PMC2212847 DOI: 10.1084/jem.20042155] [Citation(s) in RCA: 244] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
A long-standing paradox in the study of T cell antigen recognition is that of the high specificity–low affinity T cell receptor (TCR)–major histocompatibility complex peptide (MHCp) interaction. The existence of multivalent TCRs could resolve this paradox because they can simultaneously improve the avidity observed for monovalent interactions and allow for cooperative effects. We have studied the stoichiometry of the TCR by Blue Native–polyacrylamide gel electrophoresis and found that the TCR exists as a mixture of monovalent (αβγɛδɛζζ) and multivalent complexes with two or more ligand-binding TCRα/β subunits. The coexistence of monovalent and multivalent complexes was confirmed by electron microscopy after label fracture of intact T cells, thus ruling out any possible artifact caused by detergent solubilization. We found that although only the multivalent complexes become phosphorylated at low antigen doses, both multivalent and monovalent TCRs are phosphorylated at higher doses. Thus, the multivalent TCRs could be responsible for sensing low concentrations of antigen, whereas the monovalent TCRs could be responsible for dose-response effects at high concentrations, conditions in which the multivalent TCRs are saturated. Thus, besides resolving TCR stoichiometry, these data can explain how T cells respond to a wide range of MHCp concentrations while maintaining high sensitivity.
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Affiliation(s)
- Wolfgang W A Schamel
- Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas, Universidad Autónoma de Madrid, Madrid 28049, Spain.
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34
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Abstract
Helper T (Th) cell-regulated B cell immunity progresses in an ordered cascade of cellular development that culminates in the production of antigen-specific memory B cells. The recognition of peptide MHC class II complexes on activated antigen-presenting cells is critical for effective Th cell selection, clonal expansion, and effector Th cell function development (Phase I). Cognate effector Th cell-B cell interactions then promote the development of either short-lived plasma cells (PCs) or germinal centers (GCs) (Phase II). These GCs expand, diversify, and select high-affinity variants of antigen-specific B cells for entry into the long-lived memory B cell compartment (Phase III). Upon antigen rechallenge, memory B cells rapidly expand and differentiate into PCs under the cognate control of memory Th cells (Phase IV). We review the cellular and molecular regulators of this dynamic process with emphasis on the multiple memory B cell fates that develop in vivo.
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35
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de la Fuente H, Mittelbrunn M, Sánchez-Martín L, Vicente-Manzanares M, Lamana A, Pardi R, Cabañas C, Sánchez-Madrid F. Synaptic clusters of MHC class II molecules induced on DCs by adhesion molecule-mediated initial T-cell scanning. Mol Biol Cell 2005; 16:3314-22. [PMID: 15872088 PMCID: PMC1165413 DOI: 10.1091/mbc.e05-01-0005] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Initial adhesive contacts between T lymphocytes and dendritic cells (DCs) facilitate recognition of peptide-MHC complexes by the TCR. In this report, we studied the dynamic behavior of adhesion and Ag receptors on DCs during initial contacts with T-cells. Adhesion molecules LFA-1- and ICAM-1,3-GFP as well as MHC class II-GFP molecules were very rapidly concentrated at the DC contact area. Binding of ICAM-3, and ICAM-1 to a lesser extent, to LFA-1 expressed by mature but not immature DC, induced MHC-II clustering into the immune synapse. Also, ICAM-3 binding to DC induced the activation of the Vav1-Rac1 axis, a regulatory pathway involved in actin cytoskeleton reorganization, which was essential for MHC-II clustering on DCs. Our results support a model in which ICAM-mediated MHC-II clustering on DC constitutes a priming mechanism to enhance antigen presentation to T-cells.
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Affiliation(s)
- Hortensia de la Fuente
- Servicio de Inmunología, Hospital de la Princesa, Universidad Autónoma de Madrid, 28006 Madrid, Spain
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36
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Witt C, Raychaudhuri S, Chakraborty AK. Movies, measurement, and modeling: the three Ms of mechanistic immunology. ACTA ACUST UNITED AC 2005; 201:501-4. [PMID: 15728232 PMCID: PMC2213049 DOI: 10.1084/jem.20050197] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Immunological phenomena that were once deduced from genetic, biochemical, and in situ approaches are now being witnessed in living color, in three dimensions, and in real time. The information in time-lapse imaging can provide valuable mechanistic insight into a host of processes, from cell migration to signal transduction. What we need now are methods to quantitate these new visual data and to exploit computational resources and statistical mechanical methods to develop mechanistic models.
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Affiliation(s)
- Colleen Witt
- University of California, Berkeley, CA 94720, USA
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37
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Dieckmann D, Schultz ES, Ring B, Chames P, Held G, Hoogenboom HR, Schuler G. Optimizing the exogenous antigen loading of monocyte-derived dendritic cells. Int Immunol 2005; 17:621-35. [PMID: 15824067 DOI: 10.1093/intimm/dxh243] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Dendritic cell (DC) vaccination, i.e. the adoptive transfer of antigen-loaded DC, is still at an early stage and requires standardization. In this study, we investigated the exogenous loading of monocyte-derived DCs with HLA class I- and II-restricted peptides, as despite widespread use, little effort has been put into its pre-clinical validation. We found that only mature DCs (m-DC) but not immature DCs (im-DC) could be sufficiently loaded with exogenous class I-restricted peptides and were by far superior in expanding CD8(+) primary (Melan-A.A2 peptide-specific) and recall [Influenza matrix peptide (IMP) A2-specific] T cell responses. Primary stimulation with peptide-loaded im-DCs even down-regulated antigen-specific T cell responses. Our results indicate that stimulation with m-DCs is superior in terms of quantity and quality compared with im-DCs, supporting their preferred use in clinical DC trials. Loading of m-DCs with high (10 microM) concentrations generated clearly more Melan-A effectors than loading with 1 or 0.1 microM without any negative effect on the quality (affinity) of the resulting T cells. In contrast to the findings with the Melan-A peptide loading with 10 microM IMP was counter-productive, induced apoptosis and yielded fewer specific T cells of inferior affinity as compared with loading with 1 or 0.1 microM. In sharp contrast to the situation for HLA class I, much higher levels and longer half-lives of peptide-HLA class II complexes were obtainable upon loading of im-DCs with exogenous peptide, but m-DCs were functionally preferable to induce T(h)1 responses in vitro. Another surprising finding was that, while presentation to T cells upon simultaneous loading of several peptides with highly varying affinities and competing for the same class I or II molecule was possible, in priming experiments peptide competition clearly inhibited T cell induction. Although peptides will obviously vary in their individual properties, our study clearly points to some important principles that should be taken into account.
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Affiliation(s)
- Detlef Dieckmann
- Department of Dermatology, University Hospital Erlangen, Erlangen, Germany.
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38
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Abstract
T lymphocytes bearing alphabeta T cell receptors are pivotal in the immune response of most vertebrates. For example, helper T cells orchestrate antibody production by B cells as well as stimulating other cells, whereas cytotoxic T cells kill virally infected or abnormal cells. Regulatory T cells act to dampen responsiveness, and natural killer-like T cells monitor lipid metabolism. The specificity of these cells is governed by the alphabeta T cell receptors - antibody-like heterodimeric receptors that detect antigenic fragments (peptides) or lipids bound to histocompatibility molecules. Intriguing clues as to how these peculiar ligands are recognized have gradually emerged over the years and tell a remarkable story of biochemical and cellular novelty. Here we summarize some of the more recent work on alphabeta T cell receptor recognition and discuss the implications for activation.
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Affiliation(s)
- Michelle Krogsgaard
- The Howard Hughes Medical Institute and Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, California 94305, USA
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39
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Laugel B, Boulter JM, Lissin N, Vuidepot A, Li Y, Gostick E, Crotty LE, Douek DC, Hemelaar J, Price DA, Jakobsen BK, Sewell AK. Design of Soluble Recombinant T Cell Receptors for Antigen Targeting and T Cell Inhibition. J Biol Chem 2005; 280:1882-92. [PMID: 15531581 DOI: 10.1074/jbc.m409427200] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The use of recombinant T cell receptors (TCRs) to target therapeutic interventions has been hindered by the naturally low affinity of TCR interactions with peptide major histocompatibility complex ligands. Here, we use multimeric forms of soluble heterodimeric alphabeta TCRs for specific detection of target cells pulsed with cognate peptide, discrimination of quantitative changes in antigen display at the cell surface, identification of virus-infected cells, inhibition of antigen-specific cytotoxic T lymphocyte activation, and identification of cross-reactive peptides. Notably, the A6 TCR specific for the immunodominant HLA A2-restricted human T cell leukemia virus type 1 Tax(11-19) epitope bound to HLA A2-HuD(87-95) (K(D) 120 microm by surface plasmon resonance), an epitope implicated as a causal antigen in the paraneoplastic neurological degenerative disorder anti-Hu syndrome. A mutant A6 TCR that exhibited dramatically increased affinity for cognate antigen (K(D) 2.5 nm) without enhanced cross-reactivity was generated; this TCR demonstrated potent biological activity even as a monomeric molecule. These data provide insights into TCR repertoire selection and delineate a framework for the selective modification of TCRs in vitro that could enable specific therapeutic intervention in vivo.
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Affiliation(s)
- Bruno Laugel
- The T-cell Modulation Group, The Peter Medawar Building for Pathogen Research, University of Oxford, South Parks Rd., Oxford OX1 3SY, United Kingdom
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40
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Poloso NJ, Muntasell A, Roche PA. MHC class II molecules traffic into lipid rafts during intracellular transport. THE JOURNAL OF IMMUNOLOGY 2004; 173:4539-46. [PMID: 15383586 DOI: 10.4049/jimmunol.173.7.4539] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
There have been many studies demonstrating that a portion of MHC class II molecules reside in detergent-insoluble membrane domains (commonly referred to as lipid rafts). We have proposed that the function of raft association is to concentrate specific MHC class II-peptide complexes in plasma membrane microdomains that can facilitate efficient T cell activation. We now show that MHC class II becomes lipid raft associated before binding antigenic peptides. Using pulse-chase radiolabeling techniques, we find that newly synthesized MHC class II and MHC class II-invariant chain complexes initially reside in a detergent-soluble membrane fraction and acquire detergent insolubility as they traffic to lysosomal Ag processing compartments. Monensin, an inhibitor of protein transport through the Golgi apparatus, blocks association of newly synthesized MHC class II with lipid rafts. Treatment of cells with leupeptin, which inhibits invariant chain degradation, leads to the accumulation of MHC class II in lipid rafts within the lysosome-like Ag-processing compartments. Raft fractionation of lysosomal membranes confirmed the presence of MHC class II in detergent-insoluble microdomains in Ag-processing compartments. These findings indicate that newly synthesized MHC class II complexes are directed to detergent-insoluble lipid raft microdomains before peptide loading, a process that may facilitate the loading of similar peptides on MHC class II complexes in these microdomains.
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Affiliation(s)
- Neil J Poloso
- Experimental Immunology Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
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41
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Peng KW, Holler PD, Orr BA, Kranz DM, Russell SJ. Targeting virus entry and membrane fusion through specific peptide/MHC complexes using a high-affinity T-cell receptor. Gene Ther 2004; 11:1234-9. [PMID: 15215883 DOI: 10.1038/sj.gt.3302286] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The T-cell receptor (TCR) determines the specificity of T-cell recognition by binding to peptide fragments of intracellular proteins presented at the cell surface in association with molecules of the major histocompatibility complex (MHC). Engagement of the TCR by its cognate peptide/MHC ligand, with appropriate co-stimulatory signals, leads to activation of T-cell effector functions. Here we show that the attachment proteins of attenuated measles viruses, engineered to display a high-affinity single-chain TCR (scTCR), can recognize and bind to specific peptide-MHC complexes and thereby mediate targeted virus-cell entry and cell-to-cell fusion. Using the 2C TCR and its peptide/MHC ligand (SIYRYYGL/mouse K(b)), we show that a scTCR grafted onto the measles virus H protein confers new specificity to virus entry and cell fusion. The efficiency of TCR-mediated virus entry was dependent on the number of peptide/MHC complexes expressed on the target cells, increasing progressively above densities higher than 2500 complexes per cell. This work introduces a new paradigm for targeting virus entry and membrane fusion by extending the repertoire of targets to specific peptide-MHC ligands and offering a novel quantitative readout for the cellular expression of peptide-MHC complexes.
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Affiliation(s)
- K-W Peng
- Molecular Medicine Program, Mayo Clinic College of Medicine, Rochester, MN 55905, USA
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42
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Poloso NJ, Roche PA. Association of MHC class II-peptide complexes with plasma membrane lipid microdomains. Curr Opin Immunol 2004; 16:103-7. [PMID: 14734117 DOI: 10.1016/j.coi.2003.11.009] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Activation of CD4(+) T cells requires the interaction of multiple T-cell receptors with MHC class II-peptide complexes on the surface of antigen-presenting cells (APCs). Recent studies have shown that MHC class II complexes are clustered in APC plasma membrane microdomains, thereby providing a mechanism for localized concentration of MHC class II-peptide complexes. The integrity of one type of APC membrane microdomain, the lipid raft, is important for antigen presentation to T cells. We propose a model in which the coordinated processes of MHC class II peptide loading and intracellular trafficking enhance T-cell activation by loading specific MHC class II-peptide complexes in discrete lipid raft microdomains.
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Affiliation(s)
- Neil J Poloso
- Experimental Immunology Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
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43
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Mareeva T, Lebedeva T, Anikeeva N, Manser T, Sykulev Y. Antibody specific for the peptide.major histocompatibility complex. Is it T cell receptor-like? J Biol Chem 2004; 279:44243-9. [PMID: 15302863 DOI: 10.1074/jbc.m407021200] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Antibodies recognizing peptide bound to a major histocompatibility complex (MHC) protein usually have a higher affinity for the composite peptide.MHC (pMHC) ligand than T cell receptors (TCR) with the same specificity. Because the solvent-accessible peptide area constitutes only a small portion of the contacting pMHC surface, we hypothesized that the contribution of the MHC moiety to the TCR-pMHC complex stability is limited, ensuring a small increment of the binding energy delivered by the peptide to be distinguishable by the TCR or the peptide-specific antibody. This suggests that the gain in affinity of the antibody-pMHC interaction can be achieved through an increase in the on-rate without a significant change in the off-rate of the interaction. To test the hypothesis, we have analyzed the binding of an ovalbumin peptide (pOV8) and its variants associated with soluble H-2Kb protein to the 25-D1.16 monoclonal antibody and compared it with the binding of the same pMHC complexes to the OT-1 TCR. This comparison revealed a substantially higher on-rate of the antibody-pMHC interaction compared with the TCR-pMHC interaction. In contrast, both the antibody and the TCR-pMHC complexes exhibited comparably fast off-rates. Sequencing of the 25-D1.16 VH and VL genes showed that they have very few somatic mutations and those occur mainly in framework regions. We propose that the above features constitute a signature of the recognition of MHC-bound peptide antigens by TCR and TCR-like antibodies, which could explain why the latter are rarely produced in vivo.
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Affiliation(s)
- Tatiana Mareeva
- Department of Microbiology and Immunology, Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA
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44
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Boes M, Cuvillier A, Ploegh H. Membrane specializations and endosome maturation in dendritic cells and B cells. Trends Cell Biol 2004; 14:175-83. [PMID: 15066635 DOI: 10.1016/j.tcb.2004.02.004] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Interest in the cell biology of antigen presentation is centered on dendritic cells (DCs) as initiators of the immune response. The ability to examine primary antigen-presenting cells, as opposed to cell lines, has opened a new window for study of antigen processing and peptide acquisition by Class II major histocompatibility complex (MHC) products, especially where intracellular trafficking of peptide-Class-II complexes is concerned. Here, we review the dynamics of Class II MHC-positive intracellular structures in dendritic cells as well as B cells. We focus on the generation of multivesicular bodies, where Class II MHC products acquire antigenic peptide, on the endosomal transport of peptide-loaded Class II MHC to the cell surface and on the importance of Class II MHC localization in membrane microdomains.
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Affiliation(s)
- Marianne Boes
- Department of Pathology, Harvard Medical School, The New Research Building, Room 836, 77 Avenue Louis Pasteur, Boston, MA 02115, USA
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45
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Krogsgaard M, Huppa JB, Purbhoo MA, Davis MM. Linking molecular and cellular events in T-cell activation and synapse formation. Semin Immunol 2004; 15:307-15. [PMID: 15001169 DOI: 10.1016/j.smim.2003.09.002] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The complex sequence of events in which T cells recognize foreign entities on other cells is not well understood. However, the development of new techniques and approaches in both the molecular and cellular aspects of this problem have provided significant insights into the mechanisms of T-cell recognition and synapse formation. In particular, we have a clearer picture of T-cell sensitivity, the role of co-stimulation in formation of the immunological synapse, and how TCR signaling acts to maintain synapse structure and potentiate the T cells over many hours of engagement. We also are aware of new complexities in the way T-cell receptor molecules bind peptide-MHC (pMHC) ligands and what that may mean for TCR scanning, cross-reactivity, and activation. Ultimately, we want to integrate these cellular aspects of T-cell recognition with key features of the molecular interactions that drive specific events.
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Affiliation(s)
- Michelle Krogsgaard
- Howard Hughes Medical Institute and the Department of Microbiology and Immunology, Stanford University, Stanford, CA 94305-5323, USA
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46
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Purbhoo MA, Irvine DJ, Huppa JB, Davis MM. T cell killing does not require the formation of a stable mature immunological synapse. Nat Immunol 2004; 5:524-30. [PMID: 15048111 DOI: 10.1038/ni1058] [Citation(s) in RCA: 426] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2003] [Accepted: 01/28/2004] [Indexed: 11/09/2022]
Abstract
A notable feature of T lymphocyte recognition on other cell surfaces is the formation of a stable mature immunological synapse. Here we use a single-molecule labeling method to directly measure the number of ligands a cytotoxic T cell engages and track the consequences of that interaction by three-dimensional video microscopy. Like helper T cells, cytotoxic T cells were able to detect even a single foreign antigen but required about ten complexes of peptide-major histocompatibility complex (pMHC) to achieve full calcium increase and to form a mature synapse. Thus, cytotoxic T cells and helper T cells are more uniform in their antigen sensitivities than previously thought. Furthermore, only three pMHC complexes were required for killing, showing that stable synapse formation and complete signaling are not required for cytotoxicity.
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Affiliation(s)
- Marco A Purbhoo
- Department of Microbiology and Immunology and the Howard Hughes Medical Institute, Stanford University School of Medicine, Stanford, California 94305, USA
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47
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André F, Chaput N, Schartz NEC, Flament C, Aubert N, Bernard J, Lemonnier F, Raposo G, Escudier B, Hsu DH, Tursz T, Amigorena S, Angevin E, Zitvogel L. Exosomes as Potent Cell-Free Peptide-Based Vaccine. I. Dendritic Cell-Derived Exosomes Transfer Functional MHC Class I/Peptide Complexes to Dendritic Cells. THE JOURNAL OF IMMUNOLOGY 2004; 172:2126-36. [PMID: 14764678 DOI: 10.4049/jimmunol.172.4.2126] [Citation(s) in RCA: 361] [Impact Index Per Article: 18.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Current immunization protocols in cancer patients involve CTL-defined tumor peptides. Mature dendritic cells (DC) are the most potent APCs for the priming of naive CD8(+) T cells, eventually leading to tumor eradication. Because DC can secrete MHC class I-bearing exosomes, we addressed whether exosomes pulsed with synthetic peptides could subserve the DC function consisting in MHC class I-restricted, peptide-specific CTL priming in vitro and in vivo. The priming of CTL restricted by HLA-A2 molecules and specific for melanoma peptides was performed: 1) using in vitro stimulations of total blood lymphocytes with autologous DC pulsed with GMP-manufactured autologous exosomes in a series of normal volunteers; 2) in HLA-A2 transgenic mice (HHD2) using exosomes harboring functional HLA-A2/Mart1 peptide complexes. In this study, we show that: 1). DC release abundant MHC class I/peptide complexes transferred within exosomes to other naive DC for efficient CD8(+) T cell priming in vitro; 2). exosomes require nature's adjuvants (mature DC) to efficiently promote the differentiation of melanoma-specific effector T lymphocytes producing IFN-gamma (Tc1) effector lymphocytes in HLA-A2 transgenic mice (HHD2). These data imply that exosomes might be a transfer mechanism of functional MHC class I/peptide complexes to DC for efficient CTL activation in vivo.
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MESH Headings
- Animals
- Antigen Presentation/immunology
- Antigens, Neoplasm
- CD8-Positive T-Lymphocytes/immunology
- CD8-Positive T-Lymphocytes/metabolism
- Cancer Vaccines/administration & dosage
- Cancer Vaccines/immunology
- Cell Differentiation/immunology
- Cell Line, Tumor
- Cell-Free System/immunology
- Cells, Cultured
- Cytotoxicity, Immunologic
- Dendritic Cells/immunology
- Dendritic Cells/metabolism
- Dendritic Cells/transplantation
- Endosomes/immunology
- Endosomes/metabolism
- Endosomes/transplantation
- Epitopes, T-Lymphocyte/administration & dosage
- Epitopes, T-Lymphocyte/immunology
- HLA-A2 Antigen/administration & dosage
- HLA-A2 Antigen/immunology
- Histocompatibility Antigens Class I/administration & dosage
- Histocompatibility Antigens Class I/immunology
- Humans
- Interphase/immunology
- Lymphocyte Activation/immunology
- MART-1 Antigen
- Mice
- Mice, Transgenic
- Neoplasm Proteins/administration & dosage
- Neoplasm Proteins/immunology
- T-Lymphocytes, Cytotoxic/immunology
- T-Lymphocytes, Cytotoxic/metabolism
- Vaccines, Subunit/administration & dosage
- Vaccines, Subunit/immunology
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Affiliation(s)
- Fabrice André
- Unité d'Immunologie, ERM0208 Institut National de la Santé et de la Recherche Médicale, Department of Clinical Biology, Institut Gustave Roussy, Villejuif, France
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48
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van den Berg HA, Rand DA. Antigen presentation on MHC molecules as a diversity filter that enhances immune efficacy. J Theor Biol 2003; 224:249-67. [PMID: 12927531 DOI: 10.1016/s0022-5193(03)00162-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
We consider the way in which antigen is presented to T cells on MHC molecules and ask how MHC peptide presentation could be optimized so as to obtain an effective and safe immune response. By analysing this problem with a mathematical model of T-cell activation, we deduce the need for both MHC restriction and high presentation selectivity. We find that the optimal selectivity is such that about one pathogen-derived peptide is presented per MHC isoform, on the average. We also indicate upper and lower bounds to the number of MHC isoforms per individual based on detectability requirements. Thus we deduce that an important role of MHC presentation is to act as a filter that limits the diversity of antigen presentation.
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49
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Dillon TJ, Karpitski V, Wetzel SA, Parker DC, Shaw AS, Stork PJS. Ectopic B-Raf expression enhances extracellular signal-regulated kinase (ERK) signaling in T cells and prevents antigen-presenting cell-induced anergy. J Biol Chem 2003; 278:35940-9. [PMID: 12855697 DOI: 10.1074/jbc.m301506200] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
T cells that receive stimulation through the T cell receptor (TCR) in the absence of costimulation become anergic and are refractory to subsequent costimulation. This unresponsiveness is associated with the constitutive activation of the small G protein, Rap1, and the lack of Ras-dependent activation of ERK. Recent studies suggest that Rap1 can activate the MAP kinase kinase kinase B-Raf that is either endogenously or ectopically expressed. Peripheral T cells generally do not express B-Raf; therefore, to test the hypothesis that ectopic expression of B-Raf could permit Rap1 to activate ERK signaling, we generated transgenic mice expressing B-Raf within peripheral T cells. This converted Rap1 into an activator of ERK, to enhance ERK activation and proliferation following TCR engagement in the absence of costimulation. When T cells were incubated with engineered APCs presenting antigen on I-Ek and expressing low levels of B7, they became anergic, displayed constitutive activation of Rap1, and were deficient in Ras and ERK activation. However, when incubated with the same APCs, T cells expressing the B-Raf transgene proliferated upon restimulation and displayed elevated ERK activation. Thus B-Raf expression and enhanced ERK activation is sufficient to prevent anergy in a model of APC-induced T cell anergy. However, studies using anti-TCR antibody-induced anergy showed that the ability of ERKs to reverse T cell anergy is dependent on the anergic model utilized.
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MESH Headings
- Animals
- Antigen-Presenting Cells/metabolism
- Antigens, CD/biosynthesis
- Antigens, Differentiation, T-Lymphocyte/biosynthesis
- Blotting, Western
- Cell Division
- Cell Nucleus/metabolism
- DNA-Binding Proteins
- Dose-Response Relationship, Drug
- Enzyme Activation
- Fibroblasts/metabolism
- Flow Cytometry
- Humans
- Jurkat Cells
- Lectins, C-Type
- Mice
- Mice, Inbred C57BL
- Mice, Transgenic
- Mitogen-Activated Protein Kinases/metabolism
- Models, Biological
- Peptides/chemistry
- Proto-Oncogene Proteins/metabolism
- Proto-Oncogene Proteins B-raf
- Proto-Oncogene Proteins c-raf/biosynthesis
- Proto-Oncogene Proteins c-raf/metabolism
- Receptors, Antigen, T-Cell/metabolism
- Signal Transduction
- T-Lymphocytes/cytology
- T-Lymphocytes/enzymology
- T-Lymphocytes/metabolism
- Tissue Distribution
- Transcription Factors
- ets-Domain Protein Elk-1
- rap1 GTP-Binding Proteins/metabolism
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Affiliation(s)
- Tara J Dillon
- Vollum Institute, Oregon Health Sciences University, Portland, Oregon 97239, USA
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Hsu DH, Paz P, Villaflor G, Rivas A, Mehta-Damani A, Angevin E, Zitvogel L, Le Pecq JB. Exosomes as a tumor vaccine: enhancing potency through direct loading of antigenic peptides. J Immunother 2003; 26:440-50. [PMID: 12973033 DOI: 10.1097/00002371-200309000-00007] [Citation(s) in RCA: 120] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Exosomes secreted by dendritic cells (DCs) contain MHC-I, MHC-II, and other accessory molecules required for antigen presentation to T cells. Previous studies have shown that exosome MHC-I "indirectly" loaded by adding peptides to DC cultures are immunogenic. However, analysis of peptide binding was not performed to link T-cell-stimulating activity with the amount of MHC-I/peptide complexes on the exosomes. In this study, we measured peptide binding to MHC-I under different loading conditions and tested the exosomes' potencies in T-cell activation assays. We demonstrate that MHC-I on purified exosomes can be directly loaded with peptide at much greater levels than indirect loading. The direct loading method performed in mildly acidic conditions was effective even in the absence of exogenous beta2m. This increase in peptide binding greatly enhanced exosome potency, allowing us to further study the biologic activity of exosomes in vitro. In the presence of antigen-presenting cells (APC), exosomes directly loaded with the HLA-A2 restricted MART1 tumor peptide stimulated an HLA-A2/MART1 specific T-cell line. The T cells responded to exosomes using HLA-A2neg APC, demonstrating transfer of functional MHC-I/peptide complexes and not peptide alone to APC. MHC-II molecules, which are abundantly expressed on DC exosomes, were also functionally loaded under the same conditions as MHC-I. This feature allows for delivery of multiple peptide antigens that can stimulate both CD8+ cytotoxic T cells as well CD4+ T helper cells critical for an effective antitumor response. The optimized loading conditions and the ability to transfer both MHC-I and MHC-II antigens to APC have led to the development of exosomes as an "acellular" immunotherapy approach currently being tested in clinical trials.
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Affiliation(s)
- Di-Hwei Hsu
- Anosys, Inc., 1014 Hamilton Court, Menlo Park, CA 94025, USA
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