Cutting Edge: Generation of Effector Cells That Localize to Mucosal Tissues and Form Resident Memory CD8 T Cells Is Controlled by mTOR

Mucosal tissues are subject to frequent pathogen exposure and are major sites for transmission of infectious disease. CD8 T cells play a critical role in controlling mucosa-acquired infections even though their migration into mucosal tissues is tightly regulated. The mechanisms and signals that control the formation of tissue-resident memory CD8 T cells are poorly understood; however, one key regulator of memory CD8 T cell differentiation, mammalian target of rapamycin kinase, can be inhibited by rapamycin. We report that, despite enhancing the formation of memory CD8 T cells in secondary lymphoid tissues, rapamycin inhibits the formation of resident memory CD8 T cells in the intestinal and vaginal mucosa. The ability of rapamycin to block the formation of functional resident CD8 T cells in mucosal tissues protected mice from a model of CD8 T cell-mediated lethal intestinal autoimmunity. These findings demonstrate an opposing role for mammalian target of rapamycin in the formation of resident versus nonresident CD8 T cell immunity.