CEACAM marks intratumoral Tregs that exhibited highly suppressive and activated phenotypes

Abstract Regulatory T cells (Tregs) exert immunosuppressive functions and hamper anti-tumor immune responses in the tumor microenvironment. Understanding heterogeneity of intratumoral Tregs, how it changes with progression, will provide clues regarding novel target molecules Treg-directed therapies. Here we characterized phenotypes suppressive function Tregs from tissues 42 patients renal cell carcinoma using multicolor flow cytometry, RNA sequencing, vitro functional assay. We found that carcinoembryonic antigen-related adhesion molecule 1 (CEACAM1) was selectively expressed on while its expression peripheral or other minimal. CEACAM1 +intratumoral accumulated −subset did not. Notably, marked exhibited highly activated substantial clonal expansion. Depletion CEACAM1-expressing tumor-infiltrating leukocytes led to increased effector exhausted cells. Moreover, +cell depletion further enhanced anti-PD-1-–mediated reinvigoration CD8 +T Collectively, our results demonstrate delineates subset can be a for selective Tregs.