Within the tumor microenvironment of Cbx3/HP1γ-insufficient mice or wt mice treated with Cbx3/HP1γ-insufficient CD8+ T cells, we detect an increase of Klrk1/NKG2D+ infiltrating CD8+ effector T cells, a concomitant decrease in CD4+ Treg cells. The gene discussed is CD8A; the disease is neoplasm.