2024/12/13 by Ming Z. M. Zheng, Lauren Burmas, Hyon‐Xhi Tan +7 · 1 voice · 2 citations
Immunology and Microbiology · #T-cell and B-cell Immunology #Immunotherapy and Immune Responses #Immune Cell Function and Interaction
paper · pdf · doi:10.1101/2024.12.10.627643
Abstract AIM assays are thought to detect antigen (Ag)-specific T cell responses in an HLA- and cytokine-independent manner. Recent studies using AIM assays identified prominent Th17-like (CCR6 + ) CD4 + T cells and circulating follicular T helper cells (cTfh) in anti-viral contexts, but were not observed with peptide/HLA tetramer staining. We demonstrate that CD39 + Treg-like and CD26 hi Th22-like cells can be activated by cytokines in a TCR-independent manner during in vitro Ag stimulation, leading to non-specific upregulation of prototypical AIM readouts. Transcriptional analysis of memory CD4 + T cells that underwent TCR-dependent or -independent activation enabled discrimination of bona fide Ag-specific T cells from cytokine-activated Treg and Th22 cells. CXCR4 downregulation emerged as a hallmark of clonotypic expansion and TCR-dependent activation in memory CD4 + T cells and cTfh. Tracking tetramer-binding cells during re-stimulation showed that CXCR4 - CD137 + cells provide a more accurate measure of the Ag-specific population than standard AIM readouts. This modified assay excludes the predominately CCR6 + cytokine-activated T cells that contribute to an average 12-fold overestimation of the Ag-specific population. As AIM assays enable the rapid study of T cell responses against emerging pathogens, our findings provide a highly accurate approach to characterize genuine Ag-specific T cell responses that contribute to protective immunity.