Tissue-specific regulation of human secondary lymphoid organ responses: a systems approach 2307169

Abstract Introduction Naïve B and T cells are activated within secondary lymphoid organs (SLOs) — either lymph nodes (LNs) or the spleen. Depending on the metabolic and antigenic environment during activation, lymphocytes alter their differentiation trajectories to adapt to the tissue of activation (ie, a4b7 induction by retinoic acid signaling). Despite the knowledge that organs have vastly different microenvironments, we know relatively little about lymphocyte fates in SLOs draining distinct organs in humans. Methods We profiled major SLO immune cell subtypes in human PBMCs and matched spleen or pancreatic lymph nodes (pancLN) using a 39-plex CyTOF panel. Following our initial assay, we then screened T, B, stromal, and myeloid subsets from 6 SLO regions (spleen, tonsil, inguinal, mesenteric, lung, and pancreatic LN) and PBMCs for expression of a total of 345 protein antigens using cytometry by time of flight (CyTOF). Results We find a donor-consistent pattern of CD69+ CD4 and CD8+ T cells, across naïve, effector and memory subsets, preferentially present in pancLNs. These CD69+ T cells have differing proteomic characteristics from their CD69- counterparts, within the same subset. Additionally, through our high-content proteomic screen, we identify protein antigens preferentially expressed on otherwise identical phenotypic subsets in a tissue-specific manner. Conclusion T cell expression of CD69, a widespread phenomenon in pancLNs, may influence the development and response to pancreatic insults and thus warrants further characterization. More generally, while SLOs themselves are developmentally and functionally similar, we find tissue-driven induction of previously undiscovered activation profiles and cellular states that may modulate the immune response. Funding Source n/a Topic Categories Lymphocyte Differentiation and Peripheral Maintenance (LYM)