A primary role for human central memory cells in tissue immunosurveillance.

Central memory T cells (T _CM ) patrol lymph nodes, providing central immunosurveillance against known pathogens, but have not been described as conducting primary tissue immunosurveillance. We analyzed the expression of tissue-homing addressins in human T _CM vs effector memory T cells (T _EM ) from the same donors. In humans, the majority of human T _CM were tropic for either skin or gut, and the overall tissue tropism of T _CM was comparable to that of T _EM T _CM were present in healthy, noninflamed human skin, lung, colon, and cervix, suggesting a role for T _CM in the primary immunosurveillance of peripheral tissues. T _CM also had potent effector functions; 80% of CD8 ⁺ T _CM produced TC1/TC2/TC17/TC22 cytokines. T _CM injected into human skin-grafted mice migrated into skin and induced inflammatory eruptions comparable to T _EM -injected mice. In summary, human T _CM express peripheral tissue-homing receptors at levels similar to their effector memory counterparts, are found in healthy human tissues, have impressive effector functions, and can act alone to induce skin inflammation in human engrafted mice. Our studies support a novel role for human T _CM in primary immunosurveillance of peripheral tissues and highlight the important role of this long-lived cell type in tissue-based immune responses.
(© 2018 by The American Society of Hematology.)