Resident T Cell Repertoires

Regulatory T (Treg) are present in lymphoid and non-lymphoid tissues and restrict immune activation, prevent autoimmunity and regulate inflammation. While Treg in non-lymphoid tissues are typically resident, Treg in lymph nodes (LNs) predominantly recirculate and residency of Treg in LNs is poorly studied. Here, we show that 10-20% of all Treg in LNs are memory-like resident cells. Both thymic and peripheral Treg contributed to the pool of resident Treg and their residency did not require continuous TCR signaling. Yet, resident and circulating Treg had distinct TCR repertoires and different LNs contained distinct clonal subpopulations of resident Treg. We speculate that stochastic selection and variation in antigen availability governs commitment of individual T cell clones to the resident pool in each LN. Our results describe a framework for local fine-tuning of immune responses in LNs based on previous adaptive immune responses. TCR repertoire of resident and circulating effector/memory CD4+ T cells in mesenteric lymph node