KLRG1 restricts memory T cell antitumor immunity.

Killer cell lectin-like receptor subfamily G member 1 (KLRG1) has been found on human memory T lymphocytes. However, the roles of KLRG1 on human T cells especially in tumor microenvironment have not been fully understood. Our results showed KLRG1 expression on T cells significantly increased in tumor microenvironment. KLRG1+ T cells exhibited poor proliferative capacity with decreased effector cytokine production. Meanwhile, KLRG1+ T cells expressed abundant pro-inflammatory cytokines and demonstrated high level of Foxp3 expression. KLRG1+ T cells showed decreased expression of miRNA-101 and higher expression of CtBP2. Our results indicated KLRG1 might contribute to the impaired antitumor immunity of memory T cells in tumor microenvironment. Thus, repressing KLRG1 on human memory T cells might be a novel therapeutics against cancer.