Remodeling of tumor immune microenvironment:Inhibits effector immune cell function and promotes immunosuppressive cell differentiation.Skews macrophages toward an M2-like polarization.Recruits Treg cells, suppressing CD8+ T cell function, promoting immune tolerance and gastric cancer progression.Differentially regulates PD-1 expression in Tregs vs. effector T cells. This evidence concerns the gene CD8A and gastric cancer.