CD8A and neoplasm: Furthermore, Tregs can inhibit anti-tumor immune responses in several ways:1) Tregs inhibit CTL-mediated tumor killing via TGF-β -dependent cell contact (25), promoting polarization of M2 macrophages by inhibiting IFN-γ secretion by CTL cells (26), and inhibiting the generation of memory CD8+T cell through CTLA-4 (27).