Transcriptional Regulation of Tissue-Resident Lymphocytes

Numerous innate and adaptive immune cells reside in non-lymphoid tissues, where they contribute to barrier immunity, tissue homeostasis, and immune regulation. These tissue-resident populations do not recirculate in the blood or lymphatics and adopt a unique phenotype that is distinct from immune cells in the circulation. Tissue residency has been predominantly described for memory CD8(+) T cells (tissue-resident memory T cells (T-RM)], but it is now clear that CD4 T cells, regulatory T (Treg) cells, various innate T cells, and innate lymphoid cells (ILCs) can establish residence in non-lymphoid tissues. Here we highlight distinct and common features of tissue-resident lymphocytes, with a focus on the transcriptional programs that have recently been shown to guide the establishment of tissue residency.