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Chronic HIV infection causes persistent low-grade inflammation that induces premature aging of the immune system including senescence of memory and effector CD8 T cells. To uncover the reasons of gradually diminished potency of CD8 T cells from people living with HIV, here we expose the T cells to planar lipid bilayers containing ligands for T-cell receptor and a T-cell integrins and analyze the cellular morphology, dynamics of synaptic interface formation and patterns of the cellular degranulation. We find a large fraction of phenotypically naive T cells from chronically infected people are capable to form mature synapse with focused degranulation, a signature of a differentiated T cells. Further, differentiation of aberrant naive T cells may lead to the development of anomalous effector T cells undermining their capacity to control HIV and other pathogens that could be contained otherwise. HIV infection over time is thought to result in premature aging and aberrant immune responses including the induction of immunological senescence. Here the authors show altered formation of immune synapses by naive CD8+ T cells and dysregulated synapse functioning at late differentiated stages in people living with HIV. [ABSTRACT FROM AUTHOR]

Peptide exchange technologies are essential for the generation of pMHC-multimer libraries used to probe diverse, polyclonal TCR repertoires in various settings. Here, using the molecular chaperone TAPBPR, we develop a robust method for the capture of stable, empty MHC-I molecules comprising murine H2 and human HLA alleles, which can be readily tetramerized and loaded with peptides of choice in a high-throughput manner. Alternatively, catalytic amounts of TAPBPR can be used to exchange placeholder peptides with high affinity peptides of interest. Using the same system, we describe high throughput assays to validate binding of multiple candidate peptides on empty MHC-I/TAPBPR complexes. Combined with tetramer-barcoding via a multi-modal cellular indexing technology, ECCITE-seq, our approach allows a combined analysis of TCR repertoires and other T cell transcription profiles together with their cognate antigen specificities in a single experiment. The new approach allows TCR/pMHC interactions to be interrogated easily at large scale. Peptide-MHC (pMHC) tetramers are important tools for probing T cell repertoire and adaptive immune responses. Here the authors use a molecular chaperone, TAPBPR, to develop a high-throughput, multiplexible platform for pMHC tetramer generation to facilitate simultaneous assessments of T cell repertoire/antigen specificity and transcriptome. [ABSTRACT FROM AUTHOR]

The article provides an analysis of human T-cell responses and its role in vaccine immunogenicity and natural infection. HIV vaccine development has been interfered by the inducement of antibodies that can neutralize the virus. Major improvements in the understanding of memory T-cell generation and differentiation has promted the design of vaccines that could induce antigen-specific cellular immunity.

We isolated pure, viable populations of tumor-cytolytic T cells directly from patient blood samples using flow cytometric quantification of the surface mobilization of CD107a-an integral membrane protein in cytolytic granules-as a marker for degranulation after tumor stimulation. We show that tumor-cytolytic T cells are indeed elicited in patients after cancer vaccination, and that tumor reactivity is strongly correlated with efficient T-cell recognition of peptide-bearing targets. We combined CD107a mobilization with peptide-major histocompatibility complex (P-MHC) tetramer staining to directly correlate antigen specificity and cytolytic ability on a single-cell level. This showed that tumor-cytolytic T cells with high recognition efficiency represent only a minority of peptide-specific T cells elicited in patients after heteroclitic peptide vaccination. We were also able to expand these cells to high numbers ex vivo while maintaining their cytolytic potential. These techniques will be useful not only for immune monitoring of cancer vaccine trials, but also for adoptive cellular immunotherapy after ex vivo expansion. The ability to rapidly identify and isolate tumor-cytolytic T cells would be very useful in cancer immunotherapy. [ABSTRACT FROM AUTHOR]

Investigates the infection of human immunodeficiency virus (HIV)-specific CD4+ T cells by HIV. Stages of HIV disease; Effects of cell division and interferon-γ secretion on HIV infection of CD4+ T cells; Steps in T-cell stimulation and sorting.

The mechanisms underlying possible increased HIV-1 acquisition in adenovirus 5 (Ad5)-seropositive subjects vaccinated with Ad5–HIV-1 vectors in the Merck STEP trial remain unclear. We find that Ad5 serostatus does not predict Ad5-specific CD4+ T cell frequency, and we did not observe durable significant differences in Ad5-specific CD4+ T cells between Ad5-seropositive and Ad5-seronegative subjects after vaccination. These findings indicate no causative role for Ad5-specific CD4+ T cells in increasing HIV-1 susceptibility in the STEP trial. [ABSTRACT FROM AUTHOR]