A culture amplified multi-parametric intracellular cytokine assay (CAMP-ICC) for enhanced detection of antigen specific T-cell responses

Altered Immune Reconstitution in Allogeneic Stem Cell Transplant Recipients With Human Immunodeficiency Virus (HIV)

BACKGROUND

Persons living with human immunodeficiency virus (HIV) are at elevated risk of developing the malignant diseases that require allogeneic stem cell transplantation (ASCT). Recent data suggest that these individuals are also at an elevated risk of certain complications post-ASCT. This risk may result from preexisting HIV-related factors affecting dynamics of immune reconstitution post-ASCT. However, to date, there has been little work describing the dynamics of immune reconstitution post-ASCT in persons with HIV and none comparing these data to controls without HIV.

METHODS

We assessed T-cell reconstitution in 6 ASCT with HIV recipients (HIV+ASCT) compared to a control population of 21 ASCT without HIV recipients. In a subset of HIV+ASCT recipients we performed additional flow cytometry profiling of CD8+ T-cell subsets and antigen specificity of reconstituting CD4+ and CD8+ T cells.

RESULTS

We observe no difference in post-ASCT CD4+ T cells between HIV+ASCT and HIV-negative ASCT recipients, despite much lower pre-ASCT CD4+ T-cell counts in the HIV+ASCT group. In contrast, we observed significantly higher CD8+ T-cell numbers in the HIV+ASCT group post-ASCT. The reconstituting CD8+ T-cells were predominantly CD45RO+, whereas homing markers and antigen specificity of these cells varied between participants.

CONCLUSION

This study represents the most extensive characterization of immune-reconstitution post-ASCT in persons with HIV, and the first to our knowledge to compare these data to ASCT controls without HIV. The results indicate that immune reconstitution in this group can be affected by preexisting HIV infection and post-ASCT antigen exposure.

Enhancing the Detection of Brucella-Specific CD4+ T Cell Responses in Cattle via in vitro Antigenic Expansion and Restimulation

Bovine brucellosis, cause by infection with Brucella abortus, causes reproductive failure in cattle, has a major economic impact to producers, and as a zoonoses, it is a disease of public health concern. Characterization of the protective immune response against Brucella infection is important to our understanding of disease pathogenesis and for the development of diagnostic assays and vaccines. Most of the knowledge regarding protection against Brucella comes from studies in the murine model, but less is known about the immune responses in cattle. Assessment of antigen-specific T cell frequency and functional phenotype are critical to understand the immune status of the host, characterize mechanisms of protective immunity and immunopathology, and to predict immune protection. The frequency of circulating T cells specific for a particular pathogen is often very low, making analysis of such responses difficult. Our goal was to develop a flow-cytometry based approach to better track Brucella-specific T cell responses. Using peripheral blood mononuclear cells (PMBC) from Brucella abortus strain RB51-vaccinated cattle, we optimized an in vitro stimulation protocol based on a combination of antigen and pan-T cell stimulation. We then assessed RB51-specific T cell responses by concurrently measuring proliferation and cytokine production using flow-cytometry. This methodology enhances the detection of peripheral, Brucella-specific responses in cattle following RB51 vaccination. This protocol is versatile in that it can be modified to fit other in vitro stimulation systems and additional functional or phenotypic parameters can be added for flow cytometric detection and characterization of antigen-specific T cells.

Monitoring T-Cell Responses in Translational Studies: Optimization of Dye-Based Proliferation Assay for Evaluation of Antigen-Specific Responses

Adoptive therapy with regulatory T cells or tolerance-inducing antigen (Ag)-presenting cells is innovative and promising therapeutic approach to control undesired and harmful activation of the immune system, as observed in autoimmune diseases, solid organ and bone marrow transplantation. One of the critical issues to elucidate the mechanisms responsible for success or failure of these therapies and define the specificity of the therapy is the evaluation of the Ag-specific T-cell responses. Several efforts have been made to develop suitable and reproducible assays. Here, we focus on dye-based proliferation assays. We highlight with practical examples the fundamental issues to take into consideration for implementation of an effective and sensitive dye-based proliferation assay to monitor Ag-specific responses in patients. The most critical points were used to design a road map to set up and analyze the optimal assay to assess Ag-specific T-cell responses in patients undergoing different treatments. This is the first step to optimize monitoring of tolerance induction, allowing comparison of outcomes of different clinical studies. The road map can also be applied to other therapeutic interventions, not limited to tolerance induction therapies, in which Ag-specific T-cell responses are relevant such as vaccination approaches and cancer immunotherapy.

The primary immune response to Vaccinia virus vaccination includes cells with a distinct cytotoxic effector CD4 T-cell phenotype

BACKGROUND

Smallpox was eradicated by a global program of inoculation with Vaccinia virus (VV). Robust VV-specific CD4 T-cell responses during primary infection are likely essential to controlling VV replication. Although there is increasing interest in cytolytic CD4 T-cells across many viral infections, the importance of these cells during acute VV infection is unclear.

METHODS

We undertook a detailed functional and genetic characterization of CD4 T-cells during acute VV-infection of humans. VV-specific T-cells were identified by up-regulation of activation markers directly ex vivo and through cytokine and co-stimulatory molecule expression. At day-13-post primary inoculation with VV, CD38highCD45RO+ CD4 T-cells were purified by cell sorting, RNA isolated and analysed by microarray. Differential expression of up-regulated genes in activated CD4 T-cells was confirmed at the mRNA and protein levels. We compared analyses of VV-specific CD4 T-cells to studies on 12 subjects with primary HIV infection (PHI). VV-specific T-cells lines were established from PBMCs collected post vaccination and checked for cytotoxicity potential.

RESULTS

A median 11.9% CD4 T-cells were CD38highCD45RO+ at day-13 post-VV inoculation, compared to 3.0% prior and 10.4% during PHI. Activated CD4 T-cells had an up-regulation of genes related to cytolytic function, including granzymes K and A, perforin, granulysin, TIA-1, and Rab27a. No difference was seen between CD4 T-cell expression of perforin or TIA-1 to VV and PHI, however granzyme k was more dominant in the VV response. At 25:1 effector to target ratio, two VV-specific T-cell lines exhibited 62% and 30% cytotoxicity respectively and CD107a degranulation.

CONCLUSIONS

We show for the first time that CD4 CTL are prominent in the early response to VV. Understanding the role of CD4 CTL in the generation of an effective anti-viral memory may help develop more effective vaccines for diseases such as HIV.

Proliferation assay amplification by IL-2 in model primary and recall antigen systems

Background

It can be difficult to register a weak proliferative response of T lymphocytes to an antigen, particularly in a simple culture system of peripheral blood mononuclear cells (PBMC). Here we assess the usefulness of the cytokine IL-2 in amplifying such a response.

Methods

PBMC from healthy donors were cultured in the presence or absence of keyhole limpet haemocyanin (KLH), an antigen to which people have not been previously exposed. IL-2 was added from the beginning or on the fifth day of culture. Proliferation was determined by incorporation of tritiated thymidine at eight days. The recall antigen, tuberculin PPD, provided a positive control.

Results

IL-2 added at the beginning of culture can induce extremely high levels of proliferation even in the absence of antigen. However, when added on the fifth day it allowed the clear observation of a proliferative response to KLH that was barely detectable in its absence. Added late it was similarly able to boost low responses to PPD and to the mitogens lipopolysaccharide and poly(I:C), but it had no such effect with pokeweed mitogen.

Conclusions

IL-2 added late in culture is highly effective in increasing the sensitivity of T lymphocyte proliferative assays.

Intracellular cytokine detection by fluorescence-activated flow cytometry: basic principles and recent advances

Intracellular cytokine staining is a flow cytometric technique consisting of culturing stimulated cytokine-producing cells in the presence of a protein secretion inhibitor, followed by fixation, permeabilization and staining of intracellular cytokines and cell markers (surface or cytoplasmic) with fluorescent antibodies. Up to 18 different colors can be detected by modern flow cytometers, making it the only immunological technique allowing simultaneous determination of antigen-specific T cell function and phenotype. In addition, cell proliferation and viability can be also measured. For this reason, it is probably the most popular method to measure antigenicity during vaccine trials and in the study of infectious diseases, along with ELISPOT. In this review, we will summarize its features, provide the protocol used by most laboratories and review its most recent applications.

The Sydney Blood Bank Cohort: implications for viral fitness as a cause of elite control

PURPOSE OF REVIEW

The Sydney Blood Bank Cohort comprised eight individuals who were infected with an attenuated, nef/LTR-deleted strain of HIV-1 from a single donor. All six recipients with sufficient follow-up, as well as the donor, were long-term nonprogressors. Only three recipients have maintained undetectable plasma viral loads, allowing investigation of factors that determined elite control of attenuated HIV-1 infection.

RECENT FINDINGS

Follow-up of recipients showed that infection with this attenuated HIV-1 strain resulted in either low or absent viral replication in vivo for up to 29 years. The three patients without detectable viraemia have been studied for virological, genetic and immunological correlates of elite control. CD4 proliferation in vitro in response to p24 provided the clearest distinction of elite controllers from the slow progressors. Host factors are believed to differentiate the three elite controllers; only one, C135, has identifiable genetic polymorphisms that probably contributed to nonprogression: Δ32 CCR5 heterozygosity, HLA-B57 and HLA-DR13 alleles, in addition to infection with nef-defective HIV-1.

SUMMARY

Even nef-defective HIV-1 can lead to sufficient replication in vivo to enable viral evolution and eventual progression to immunodeficiency. Host factors modified the outcome of infection with attenuated HIV-1, as exemplified by the unique patient C135.

Decreased expression in nuclear factor-κB essential modulator due to a novel splice-site mutation causes X-linked ectodermal dysplasia with immunodeficiency

X-linked ectodermal dysplasia with immunodeficiency (XL-ED-ID) is caused by hypomorphic mutations in NEMO, which encodes nuclear factor-kappaB (NF-κB) essential modulator. We identified a novel mutation, 769-1 G>C, at the splicing acceptor site of exon 7 in NEMO in a Japanese patient with XL-ED-ID. Although various abnormally spliced NEMO messenger RNAs (mRNAs) were observed, a small amount of wild-type (WT) mRNA was also identified. Decreased NEMO protein expression was detected in various lineages of leukocytes. Although one abnormally spliced NEMO protein showed residual NF-κB transcription activity, it did not seem to exert a dominant-negative effect against WT-NEMO activity. CD4(+) T cell proliferation was impaired in response to measles and mumps, but not rubella. These results were consistent with the clinical and laboratory findings of the patient, suggesting the functional importance of NEMO against specific viral infections. The 769-1 G>C mutation is responsible for decreased WT-NEMO protein expression, resulting in the development of XL-ED-ID.