Tissue‐resident regulatory T cells accumulate at human barrier lymphoid organs

Regulatory T cells (Tregs) play a critical role in immune regulation and peripheral tolerance. While different types of Tregs have been identified both mice humans, much our understanding about how these maintain homeostasis is derived from animal models. In this study, we examined two distinct human lymphoid organs to understand repeated exposure infections at the mucosal surface influences phenotype tissue localization Tregs. We show that while tonsils spleen express tissue-resident phenotype, they accumulate greater numbers tonsils. Tonsillar-resident exhibit highly suppressive with significantly increased expression CD39, ICOS CTLA-4 compared their counterparts circulation or spleen. Functionally, resident are able effectively suppress cell proliferation. further demonstrate tonsillar-resident share key features follicular helper cells. Spatial analysis reveals vast majority localized border T-zone B follicle, as well within lymphocyte pockets enriched memory Together findings suggest strategically co-localized sites recurrent inflammation.