IL-15 Complexes Induce Migration of Resting Memory CD8 T Cells into Mucosal Tissues.

IL-15 is an essential cytokine known to promote T cell survival and activate the effector function of memory phenotype CD8 T cells. Blocking IL-15 signals also significantly impacts tissue-specific effector and memory CD8 T cell formation. In this study, we demonstrate that IL-15 influences the generation of memory CD8 T cells by first promoting their accumulation into mucosal tissues and second by sustaining expression of Bcl-6 and T-bet. We show that the mechanism for this recruitment is largely dependent on mammalian target of rapamycin and its subsequent inactivation of FoxO1. Last, we show that IL-15 complexes delivered locally to mucosal tissues without reinfection is an effective strategy to enhance establishment of tissue resident memory CD8 T cells within mucosal tissues. This study provides mechanistic insight into how IL-15 controls the generation of memory CD8 T cells and influences their trafficking and ability to take up residence within peripheral tissues.