Lymph nodes and Peyer’s patches harbor resident CD4+ T cells that accumulate after prolonged antigen exposure (CAM1P.230)

CD4 + T cells can acquire various migratory properties after immune responses to provide enhanced immuno-surveillance together with effective protection. However, the comprehensive analysis of these migratory properties has been difficult due to the highly dynamic nature of T cell circulation. We developed two independent methods to analyze the migration of effector/memory CD4 + T cells by long-term in vivo cell tracking. We identified a resident population of effector/memory CD4 + T cells that stays in lymph nodes and Peyer’s patches (PPs) without circulation or proliferation. Resident CD4 + T cells constitute up to 50% of all effector/memory cells, including, but not limited to, follicular helper T cells. This heterogeneous population of resident cells expresses low levels of egress-promoting sphingosine-1-phosphate receptor 1 ( S1pr1 ) and possesses a distinct TCR repertoire. Furthermore, resident cells constituted a significant portion of all CD4 + T cells in PPs and accumulated in these organs after continuous antigen exposure. Our results define a previously unrecognized population of effector/memory CD4 + T cells in lymphoid tissues which might perform similar functions as non-lymphoid tissue-resident memory T cells.