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Davis MM, Andreae M, Freed GL. Physicians' early challenges related to the pneumococcal conjugate vaccine. AMBULATORY PEDIATRICS : THE OFFICIAL JOURNAL OF THE AMBULATORY PEDIATRIC ASSOCIATION 2001; 1:302-5. [PMID: 11888419 DOI: 10.1367/1539-4409(2001)001<0302:pecrtt>2.0.co;2] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
OBJECTIVE To characterize the obstacles faced by physicians regarding administration of a 7-valent pneumococcal conjugate vaccine (Prevnar) to all children younger than 2 years and to high-risk children from 2--5 years of age during the months immediately following national recommendations. DESIGN Semistructured telephone interviews. PARTICIPANTS Convenience sample (n = 24) of pediatricians and family physicians. RESULTS Eighteen physicians were recommending pneumococcal vaccine and 6 were not. Those who were recommending pneumococcal vaccine had encountered resistance from parents and variations in private and public insurance coverage. Physicians who were not recommending pneumococcal vaccine expressed concern about the cost of the vaccine and general caution in adopting new vaccine recommendations. Respondents offered several suggestions for improving the vaccine recommendation process. CONCLUSIONS This analysis of physicians' early decision making regarding pneumococcal vaccine reflects obstacles to vaccine implementation that may arise with the introduction of other childhood vaccines.
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Fahrer AM, Konigshofer Y, Kerr EM, Ghandour G, Mack DH, Davis MM, Chien YH. Attributes of gammadelta intraepithelial lymphocytes as suggested by their transcriptional profile. Proc Natl Acad Sci U S A 2001; 98:10261-6. [PMID: 11526237 PMCID: PMC56949 DOI: 10.1073/pnas.171320798] [Citation(s) in RCA: 133] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
gammadelta T lymphocytes in the intestinal intraepithelial layer (gammadelta IELs) are thought to contribute to immune competence, but their actual function remains poorly understood. Here we used DNA microarrays to study the gene expression profile of gammadelta IELs in a Yersinia infection system to better define their roles. To validate this approach, mesenteric lymph node CD8(+) alphabeta T cells were similarly analyzed. The transcription profiles show that, whereas lymph node CD8(+) alphabeta T cells must be activated to become cytotoxic effectors, gammadelta IELs are constitutively activated and appear to use different signaling cascades. Our data suggest that gammadelta IELs may respond efficiently to a broad range of pathological situations irrespective of their diverse T cell antigen receptor repertoire. gammadelta IELs may modulate local immune responses and participate in intestinal lipid metabolism, cholesterol homeostasis, and physiology. This study provides a strong basis for further investigations of the roles of these cells as well as mucosal immune defense in general.
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MESH Headings
- Animals
- Antigen Presentation
- CD8-Positive T-Lymphocytes/immunology
- Cholesterol/metabolism
- Cytotoxicity, Immunologic
- Female
- Gene Expression
- Immunity, Mucosal
- Intestinal Mucosa/immunology
- Intestinal Mucosa/metabolism
- Lipid Metabolism
- Lymphocyte Activation
- Mice
- Mice, Inbred C57BL
- Oligonucleotide Array Sequence Analysis
- Receptors, Antigen, T-Cell, gamma-delta/genetics
- Receptors, Antigen, T-Cell, gamma-delta/metabolism
- Signal Transduction
- T-Lymphocyte Subsets/immunology
- Transcription, Genetic
- Yersinia pseudotuberculosis Infections/genetics
- Yersinia pseudotuberculosis Infections/immunology
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103
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He XS, Rehermann B, Boisvert J, Mumm J, Maecker HT, Roederer M, Wright TL, Maino VC, Davis MM, Greenberg HB. Direct functional analysis of epitope-specific CD8+ T cells in peripheral blood. Viral Immunol 2001; 14:59-69. [PMID: 11270597 DOI: 10.1089/08828240151061400] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The functional status of virus-specific CD8+ T cells is important for the outcome and the immunopathogenesis of viral infections. We have developed an assay for the direct functional analysis of antigen-specific CD8+ T cells, which does not require prolonged in vitro cultivation and amplification of T cells. Whole blood samples were incubated with peptide antigens for <5 h, followed by staining with peptide-MHC tetramers to identify epitope-specific T cells. The cells were also stained for the activation marker CD69 or for the production of cytokines such as interferon-gamma (IFNgamma) or tumor necrosis factor-alpha (TNFalpha). With the combined staining with tetramer and antibodies to CD69 or cytokines the number of antigen-specific CD8+ T cells as well as the functional response of each individual cell to the cognate antigen can be determined in a single experiment. Virus-specific CD8+ T cells that are nonfunctional, as well as those that are functional under the same stimulating conditions can be simultaneously detected with this assay, which is not possible by using other T-cell functional assays including cytotoxicity assay, intracellular cytokine staining, and enzyme-linked immunospot (ELISPOT) assay.
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104
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Bromley SK, Burack WR, Johnson KG, Somersalo K, Sims TN, Sumen C, Davis MM, Shaw AS, Allen PM, Dustin ML. The immunological synapse. Annu Rev Immunol 2001; 19:375-96. [PMID: 11244041 DOI: 10.1146/annurev.immunol.19.1.375] [Citation(s) in RCA: 661] [Impact Index Per Article: 28.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The adaptive immune response is initiated by the interaction of T cell antigen receptors with major histocompatibility complex molecule-peptide complexes in the nanometer scale gap between a T cell and an antigen-presenting cell, referred to as an immunological synapse. In this review we focus on the concept of immunological synapse formation as it relates to membrane structure, T cell polarity, signaling pathways, and the antigen-presenting cell. Membrane domains provide an organizational principle for compartmentalization within the immunological synapse. T cell polarization by chemokines increases T cell sensitivity to antigen. The current model is that signaling and formation of the immunological synapse are tightly interwoven in mature T cells. We also extend this model to natural killer cell activation, where the inhibitory NK synapse provides a striking example in which inhibition of signaling leaves the synapse in its nascent, inverted state. The APC may also play an active role in immunological synapse formation, particularly for activation of naïve T cells.
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MESH Headings
- Animals
- Antigen Presentation/immunology
- Cell Adhesion
- Cell Adhesion Molecules/physiology
- Cell Communication
- Cell Membrane/ultrastructure
- Cell Polarity
- Chemokines/physiology
- Cholera Toxin/pharmacology
- Immunologic Capping
- Killer Cells, Natural/immunology
- Killer Cells, Natural/ultrastructure
- Lymphocyte Activation/immunology
- Membrane Microdomains/physiology
- Membrane Microdomains/ultrastructure
- Mice
- Models, Immunological
- Receptor-CD3 Complex, Antigen, T-Cell/immunology
- Receptor-CD3 Complex, Antigen, T-Cell/ultrastructure
- Receptors, Antigen, T-Cell/immunology
- Receptors, Antigen, T-Cell/ultrastructure
- Receptors, Chemokine/physiology
- Receptors, Immunologic/immunology
- Receptors, Immunologic/physiology
- Receptors, Immunologic/ultrastructure
- Signal Transduction
- T-Lymphocyte Subsets/immunology
- T-Lymphocyte Subsets/ultrastructure
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105
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Davis MM, Bruckman D, Cabana MD, Clark SJ, Dombkowski KJ, Kemper AR, Rushton JL, Freed GL. Constructive use of race and ethnicity variables. ARCHIVES OF PEDIATRICS & ADOLESCENT MEDICINE 2001; 155:973; author reply 973-4. [PMID: 11483132] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/21/2023]
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106
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Fong L, Hou Y, Rivas A, Benike C, Yuen A, Fisher GA, Davis MM, Engleman EG. Altered peptide ligand vaccination with Flt3 ligand expanded dendritic cells for tumor immunotherapy. Proc Natl Acad Sci U S A 2001; 98:8809-14. [PMID: 11427731 PMCID: PMC37517 DOI: 10.1073/pnas.141226398] [Citation(s) in RCA: 382] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/07/2001] [Indexed: 02/07/2023] Open
Abstract
Most tumor-associated antigens represent self-proteins and as a result are poorly immunogenic due to immune tolerance. Here we show that tolerance to carcinoembryonic antigen (CEA), which is overexpressed by the majority of lethal malignancies, can be reversed by immunization with a CEA-derived peptide. This peptide was altered to make it a more potent T cell antigen and loaded onto dendritic cells (DCs) for delivery as a cellular vaccine. Although DCs are rare in the blood, we found that treatment of advanced cancer patients with Flt3 ligand, a hematopoietic growth factor, expanded DCs 20-fold in vivo. Immunization with these antigen-loaded DCs induced CD8 cytotoxic T lymphocytes that recognized tumor cells expressing endogenous CEA. Staining with peptide-MHC tetramers demonstrated the expansion of CD8 T cells that recognize both the native and altered epitopes and possess an effector cytotoxic T lymphocyte phenotype (CD45RA(+)CD27(-)CCR7(-)). After vaccination, two of 12 patients experienced dramatic tumor regression, one patient had a mixed response, and two had stable disease. Clinical response correlated with the expansion of CD8 tetramer(+) T cells, confirming the role of CD8 T cells in this treatment strategy.
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107
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Emley TE, Cain MP, Faught PR, Davis MM. Ureteropelvic junction obstruction due to inflammatory pseudotumor masquerading as hydronephrosis because of a neuropathic bladder in a child with myelomeningocele. Urology 2001; 58:105. [PMID: 11445491 DOI: 10.1016/s0090-4295(01)00970-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Inflammatory pseudotumors (IPTs), also known as inflammatory myofibroblastic tumors, are rare solid lesions, generally thought to be benign, which have been described in a variety of locations. We report a case of a child with a neuropathic bladder who developed a pseudotumor of the retroperitoneum that caused progressive ureteral obstruction distal to the ureteropelvic junction. Hydronephrosis as a complication of IPTs has been described with bladder and uterine IPTs; however, in our review of published reports, we found no reported cases of a retroperitoneal IPT causing proximal ureteral obstruction in a pediatric patient.
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108
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109
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Gupta SK, Fitzgerald JF, Croffie JM, Chong SK, Pfefferkorn MC, Davis MM, Faught PR. Experience with juvenile polyps in North American children: the need for pancolonoscopy. Am J Gastroenterol 2001; 96:1695-7. [PMID: 11419816 DOI: 10.1111/j.1572-0241.2001.03860.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
We report a recent experience with juvenile polyps (JP) in a large cohort of North American children to determine if a pancolonoscopy (PC) is needed in all children with suspected polyps. We reviewed hospital charts of all patients with JP seen over a 9-yr period (January, 1990-October, 1998). A total of 331 JP were encountered during 195 procedures in 184 patients (64% males, 88% white, mean age 5.93 yr [range 0.42-15.5 yr], median age 4.84 yr). Painless rectal bleeding was the commonest symptom. PC was performed in 42% (82/195) of procedures, and 177 JP were encountered: 54% (97/177) were in the rectosigmoid colon, 14% (24/177) were in the descending colon, and 32% (56/177) were proximal to the splenic flexure (i.e., proximal polyps). Overall, proximal polyps were seen in 37% (31/82) of PC. Only proximal polyps were noted in 12% (10/82) of PC. Five patients were re-endoscoped after an initial limited examination because of continuing symptoms from proximal polyps. All but one of the polyps had typical features of a JP on histological examination. Though most JP are located in the left colon, a PC should be the initial procedure because: 1) 37% of PC revealed proximal polyps, 2) 32% of polyps were located proximal to splenic flexure, 3) persistence of symptoms from missed proximal polyp(s) necessitates a repeat study with attendant risks, and 4) there is a possibility of malignant transformation in an unidentified JP.
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110
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Davis MM, Wülfing C, Krummel MF, Savage PA, Xu J, Sumen C, Dustin ML, Chien YH. Visualizing T-cell recognition. COLD SPRING HARBOR SYMPOSIA ON QUANTITATIVE BIOLOGY 2001; 64:243-51. [PMID: 11232292 DOI: 10.1101/sqb.1999.64.243] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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111
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Abstract
To characterize the ligand binding properties of a naive T cell repertoire capable of responding to a foreign antigen, we analyzed T cell populations from T cell receptor (TCR) beta transgenic mice using a novel, single cell peptide/major histocompatibility complex (MHC) tetramer dissociation assay. The largely CD4+CD8(-/low) antigen-specific thymocyte repertoire exhibited a broad, bimodal distribution of tetramer binding half-lives (t(1/2)s), with a significant underrepresentation in the intermediate half-life range in which the majority of the peripheral repertoire lies. Thus, cells with the potential to bind foreign antigen with the lowest and highest stability are likely to be selectively removed from the repertoire prior to their establishment in the periphery. These studies provide direct evidence that thymic selection biases the naive peripheral T cell repertoire toward TCR-ligand interactions that fall within a moderate half-life "window."
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112
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Turgeon SM, Kegel G, Davis MM. Electrolytic lesions of the medial septum enhance latent inhibition in a conditioned taste aversion paradigm. Brain Res 2001; 890:333-7. [PMID: 11164800 DOI: 10.1016/s0006-8993(00)03192-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The effects of medial septal lesions on latent inhibition (LI) were assessed in a conditioned taste aversion paradigm. Animals were tested in a LI paradigm 2 weeks after receiving medial septal or sham lesions. The LI paradigm involved a pre-exposure phase in which water-deprived rats were allowed access to either water (non-pre-exposed; NPE) or 5% sucrose (pre-exposed; PE), followed by a conditioning phase in which animals were allowed access to sucrose and subsequently injected with lithium chloride, and a test phase in which animals were allowed access to both sucrose and water. LI was assessed by comparing the %-sucrose consumed in PE and NPE groups on the test day. There was a significantly greater LI effect in the lesion group than in the sham group, suggesting that electrolytic lesions to the medial septum can enhance LI in a CTA paradigm.
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113
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Abstract
BACKGROUND/PURPOSE Anastomotic leak and stricture are common causes of morbidity after esophageal repair. The authors describe a technique of patch esophagoplasty using decellularized human skin. METHODS Twelve conditioned dogs underwent a cervical 2.0- x 1.0-cm esophagoplasty with AlloDerm. A gastrostomy tube was used for feedings until an esophagram was performed on the 10th to 14th postoperative day. Dogs were then given oral chow and followed up for leak and dysphagia. Animals were killed at 1-, 2-, and 3-month intervals and evaluated for stricture, diverticula formation, and patch histology. RESULTS All animals survived, and none had sepsis or dysphagia. All esophagrams were without evidence of leak or stricture. At death there were no strictures or diverticula. Histologic examination of 1-month specimens showed partial reepithelialization of the patch with neovascularization. Control staining of AlloDerm was strongly positive for elastin. This was decreased in the region of the patch at 1 month. Two-month specimens showed intact epithelium and an increase in the caliber of new blood vessels. Three-month specimens showed no significant variation from 2-month animals. CONCLUSION Decellularized human skin (AlloDerm) provides a temporary collagen framework on which esophageal healing can occur and function can be maintained.
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114
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DeMarco RT, Cain MP, Davis MM. Xanthogranulomatous pyelonephritis associated with a congenital caliceal diverticulum. Urology 2001; 57:168. [PMID: 11164173 DOI: 10.1016/s0090-4295(00)00843-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
We report a rare case of xanthogranulomatous pyelonephritis occurring in a caliceal diverticulum in a 1-year-old child. She presented with recurrent urinary tract infections. A computed tomography scan demonstrated an enhancing cystic lesion in the left kidney. At open exploration, a caliceal diverticulum was found with a very stenotic opening into the renal pelvis. The diverticulum was enucleated, and the pathologic examination confirmed xanthogranulomatous pyelonephritis in the parenchyma surrounding the diverticulum. The child did well postoperatively with no recurrence of her urinary tract infections.
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115
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Davis MM. How to ask questions (in 10 easy steps). Curr Biol 2000; 10:R771. [PMID: 11084345 DOI: 10.1016/s0960-9822(00)00782-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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116
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Backhaus BO, Kaefer M, Engum SA, Davis MM. Contralateral testicular metastasis in paratesticular rhabdomyosarcoma. J Urol 2000; 164:1709-10. [PMID: 11025756] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/17/2023]
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117
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Molldrem JJ, Lee PP, Wang C, Felio K, Kantarjian HM, Champlin RE, Davis MM. Evidence that specific T lymphocytes may participate in the elimination of chronic myelogenous leukemia. Nat Med 2000; 6:1018-23. [PMID: 10973322 DOI: 10.1038/79526] [Citation(s) in RCA: 508] [Impact Index Per Article: 21.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Although the immune system has long been implicated in the control of cancer, evidence for specific and efficacious immune responses in human cancer has been lacking. In the case of chronic myelogenous leukemia (CML), either allogeneic bone marrow transplant (BMT) or interferon-alpha2b (IFN-alpha2b) therapy can result in complete remission, but the mechanism for prolonged disease control is unknown and may involve immune anti-leukemic responses. We previously demonstrated that PR1, a peptide derived from proteinase 3, is a potential target for CML-specific T cells. Here we studied 38 CML patients treated with allogeneic BMT, IFN- alpha2b or chemotherapy to look for PR1-specific T cells using PR1/HLA-A*0201 tetrameric complexes. There was a strong correlation between the presence of PR1-specific T cells and clinical responses after IFN-alpha and allogeneic BMT. This provides for the first time direct evidence of a role for T-cell immunity in clearing malignant cells.
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118
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Wülfing C, Bauch A, Crabtree GR, Davis MM. The vav exchange factor is an essential regulator in actin-dependent receptor translocation to the lymphocyte-antigen-presenting cell interface. Proc Natl Acad Sci U S A 2000; 97:10150-5. [PMID: 10963677 PMCID: PMC27768 DOI: 10.1073/pnas.97.18.10150] [Citation(s) in RCA: 97] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/03/2000] [Indexed: 11/18/2022] Open
Abstract
During the interaction of a T cell with an antigen-presenting cell (APC), several receptor ligand pairs, including the T cell receptor (TCR)/major histocompatibility complex (MHC), accumulate at the T cell/APC interface in defined geometrical patterns. This accumulation depends on a movement of the T cell cortical actin cytoskeleton toward the interface. Here we study the involvement of the guanine nucleotide exchange factor vav in this process. We crossed 129 vav(-/-) mice with B10/BR 5C.C7 TCR transgenic mice and used peptide-loaded APCs to stimulate T cells from the offspring. We found that the accumulation of TCR/MHC at the T cell/APC interface and the T cell actin cytoskeleton rearrangement were clearly defective in these vav(+/-) mice. A comparable defect in superantigen-mediated T cell activation of T cells from non-TCR transgenic 129 mice was also observed, although in this case it was more apparent in vav(-/-) mice. These data indicate that vav is an essential regulator of cytoskeletal rearrangements during T cell activation.
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119
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Krummel M, Wülfing C, Sumen C, Davis MM. Thirty-six views of T-cell recognition. Philos Trans R Soc Lond B Biol Sci 2000; 355:1071-6. [PMID: 11186308 PMCID: PMC1692810 DOI: 10.1098/rstb.2000.0644] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
While much is known about the signalling pathways within lymphocytes that are triggered during activation, much less is known about how the various cell surface molecules on T cells initiate these events. To address this, we have focused on the primary interaction that drives T-cell activation, namely the binding of a particular T-cell receptor (TCR) to peptide-MHC ligands, and find a close correlation between biological activity and off-rate; that is, the most stimulatory TCR ligands have the slowest dissociation rates. In general, TCRs from multiple histocompatibility complex (MHC) class-II-restricted T cells have half-lives of 1-11s at 25 degrees C, a much narrower range than found with antibodies and suggesting a strong selection for an optimum dissociation rate. TCR ligands with even faster dissociation rates tend to be antagonists. To observe the effects of these different ligands in their physiological setting, we made gene fusions of various molecules with green fluorescent protein (GFP), transfected them into the relevant lymphocytes, and observed their movements during T-cell recognition using multicolour video microscopy. We find that clustering of CD3zeta-GFP and CD4-GFP on the Tcell occurs concomitantly or slightly before the first rise in calcium by the T cell, and that various GFP-labelled molecules on the B-cell side cluster shortly thereafter (ICAM-1, class II MHC, CD48), apparently driven byT-cell molecules. Most of this movement towards the interface is mediated by signals through the co-stimulatory receptors, CD28 and LFA-1, and involves myosin motors and the cortical actin cytoskeleton. Thus, we have proposed that the principal mechanism by which co-stimulation enhances T-cell responsiveness is by increasing the local density of T-cell activation molecules, their ligands and their attendant signalling apparatus. In collaboration with Michael Dustin and colleagues, we have also found that the formation and stability of the TCR-peptide-MHC cluster at the centre of the interaction cap between T and B cells is highly dependent on the dissociation rate of the TCR and its ligand. Thus, we are able to link this kinetic parameter to the formation of a cell surface structure that is linked to and probably causal with respect to T-cell activation.
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120
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Krummel MF, Sjaastad MD, Wülfing C, Davis MM. Differential clustering of CD4 and CD3zeta during T cell recognition. Science 2000; 289:1349-52. [PMID: 10958781 DOI: 10.1126/science.289.5483.1349] [Citation(s) in RCA: 320] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Whereas T helper cells recognize peptide-major histocompatibility complex (MHC) class II complexes through their T cell receptors (TCRs), CD4 binds to an antigen-independent region of the MHC. Using green fluorescent protein-tagged chimeras and three-dimensional video microscopy, we show that CD4 and TCR-associated CD3zeta cluster in the interface coincident with increases in intracellular calcium. Signaling-, costimulation-, and cytoskeleton-dependent processes then stabilize CD3zeta in a single cluster at the center of the interface, while CD4 moves to the periphery. Thus, the CD4 coreceptor may serve primarily to "boost" recognition of ligand by the TCR and may not be required once activation has been initiated.
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121
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122
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Abstract
All rearranging antigen receptor genes have one or two highly diverse complementarity determining regions (CDRs) among the six that typically form the ligand binding surface. We report here that, in the case of antibodies, diversity at one of these regions, CDR3 of the V(H) domain, is sufficient to permit otherwise identical IgM molecules to distinguish between a variety of hapten and protein antigens. Furthermore, we find that somatic mutation can allow such antibodies to achieve surprisingly high affinities. These results are consistent with a model in which the highly diverse CDR3 loops are the key determinant of specificity in antigen recognition in both T cell receptors (TCR) and antibodies, whereas the germline-encoded CDR1 and CDR2 sequences are much more cross-reactive.
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123
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Reay PA, Matsui K, Haase K, Wulfing C, Chien YH, Davis MM. Determination of the relationship between T cell responsiveness and the number of MHC-peptide complexes using specific monoclonal antibodies. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2000; 164:5626-34. [PMID: 10820237 DOI: 10.4049/jimmunol.164.11.5626] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
We describe the generation of three mAbs that recognize the complex of the class II MHC molecule IEk bound to a peptide derived from the carboxyl terminus of moth cytochrome c (residues 95-103). Reactivities of these mAbs are sensitive to single alterations in the sequence of both helices of the MHC molecule and to the bound peptide. The epitopes of these reagents are distinct but overlap substantially. One of these mAbs specifically blocks lymphokine release by T cells responsive to this complex but not others. We have used another to examine how the number of complexes on an APC is related to its ability to stimulate T cells. We find that 200-400 complexes per cell are necessary and sufficient to induce a degree of stimulation, whereas maximum stimulation is achieved only if more than 5000 complexes are present. The analysis indicates that T cell activation is a stochastic process.
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124
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Kasson PM, Rabinowitz JD, Schmitt L, Davis MM, McConnell HM. Kinetics of peptide binding to the class II MHC protein I-Ek. Biochemistry 2000; 39:1048-58. [PMID: 10653650 DOI: 10.1021/bi9921337] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Class II MHC glycoproteins bind short (7-25 amino acid) peptides in an extended type II polyproline-like conformation and present them for immune recognition. Because empty MHC is unstable, measurement of the rate of the second-order reaction between peptide and MHC is challenging. In this report, we use dissociation of a pre-bound peptide to generate the active, peptide-receptive form of the empty class II MHC molecule I-Ek. This allows us to measure directly the rate of reaction between active, empty I-Ek and a set of peptides that vary in structure. We find that all peptides studied, despite having highly variable dissociation rates, bind with similar association rate constants. Thus, the rate-limiting step in peptide binding is minimally sensitive to peptide side-chain structure. An interesting complication to this simple model is that a single peptide can sometimes bind to I-Ek in two kinetically distinguishable conformations, with the stable peptide-MHC complex isomer forming much more slowly than the less-stable one. This demonstrates that an additional free-energy barrier limits the formation of certain specific MHC-peptide complex conformations.
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125
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Hernández J, Lee PP, Davis MM, Sherman LA. The use of HLA A2.1/p53 peptide tetramers to visualize the impact of self tolerance on the TCR repertoire. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2000; 164:596-602. [PMID: 10623800 DOI: 10.4049/jimmunol.164.2.596] [Citation(s) in RCA: 81] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
p53 is an attractive target for cancer immunotherapy since it is overexpressed in half of all tumors. However, it is also expressed in normal lymphoid tissue, and self tolerance leaves a p53-specific repertoire purged of high avidity CTL. To better understand the mechanism of tolerance and the basis for such low avidity interaction, p53-specific CTL from p53 deficient (p53-) and sufficient (p53+) A2.1/Kb transgenic mice were compared with respect to their ability to bind HLA-A2.1 tetramers containing cognate murine p53 peptide Ag, p53 261-269. Since the murine CD8 molecule cannot interact with human HLA-A2.1, this tests the ability of the TCR to bind the A2.1/peptide complex tetramer. CTL from p53- mice demonstrated strong binding of such A2.1/p53 261-269 tetramers; however, the CTL from tolerant p53+ mice were devoid of tetramer-binding CD8+ T cells. Examination of TCR expression at the clonal level revealed that CTL from p53+ and p53- mice each expressed comparable levels of the p53-specific TCR. These results indicate that normal expression of p53 promotes elimination of T cells expressing TCRs with sufficient affinity to achieve stable binding of the A2.1/p53 261-269 tetramers.
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MESH Headings
- Amino Acid Sequence
- Animals
- Base Sequence
- Binding Sites/genetics
- Binding Sites/immunology
- Cell Line
- Clone Cells
- H-2 Antigens/genetics
- HLA-A2 Antigen/genetics
- HLA-A2 Antigen/immunology
- Humans
- Mice
- Mice, Inbred C57BL
- Mice, Transgenic
- Molecular Sequence Data
- Peptide Fragments/chemical synthesis
- Peptide Fragments/immunology
- Receptors, Antigen, T-Cell, alpha-beta/biosynthesis
- Receptors, Antigen, T-Cell, alpha-beta/genetics
- Self Tolerance/genetics
- Self Tolerance/immunology
- T-Lymphocytes, Cytotoxic/immunology
- T-Lymphocytes, Cytotoxic/metabolism
- Tumor Suppressor Protein p53/biosynthesis
- Tumor Suppressor Protein p53/genetics
- Tumor Suppressor Protein p53/immunology
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