CXCR6 promotes dermal CD8 T cell survival and transition to long-term tissue residence.

Tissue resident memory T cells (T) provide important protection against infection, and yet the interstitial signals necessary for their formation and persistence remain incompletely understood. Here we show that antigen-dependent induction of the chemokine receptor, CXCR6, is a conserved requirement for T formation in peripheral tissue after viral infection. CXCR6 was dispensable for the early accumulation of antigen-specific CD8 T cells in skin and did not restrain their exit. Single cell sequencing indicated that CXCR6 CD8 T cells were also competent to acquire a transcriptional program of residence but exhibited deficiency in multiple pathways that converged on survival and metabolic signals necessary for memory. As such, CXCR6 CD8 T cells exhibited increased rates of apoptosis relative to controls in the dermis, leading to inefficient T formation. CXCR6 expression may therefore represent a common mechanism across peripheral non-lymphoid tissues and inflammatory states that increases the probability of long-term residence.