UCSF

T cells residing in mucosal tissues play important roles in homeostasis and defense against microbial pathogens. The gut and female reproductive tract (FRT) are both tolerogenic environments, but they differ in the kinds of foreign Ags they need to tolerate. How these different environments influence the properties of their T cells is poorly understood, but important for understanding women's health. We recruited antiretroviral therapy-suppressed women living with HIV who donated, within one visit, blood and tissue samples from the ileum, colon, rectosigmoid, endometrium, endocervix, and ectocervix. With these samples, we conducted 36-parameter cytometry by time of flight phenotyping of T cells. Although gut and FRT T cells shared features discriminating them from their blood counterparts, they also harbored features distinguishing them from one another. These included increased proportions of CD69⁺ T resident memory cells of the T effector memory phenotype, as well as preferential coexpression of CD69 and CD103, on the gut-derived cells. In contrast, CD69⁺CD103⁺ T resident memory CD8⁺ T cells from FRT, but not those from gut, preferentially expressed PD1. We further determined that a recently described population of CXCR4⁺ T inflammatory mucosal cells differentially expressed multiple other chemokine receptors relative to their blood counterparts. Our findings suggest that T cells resident in different tolerogenic mucosal sites take on distinct properties.