CD8A and neoplasm: Immunosuppressive cells include CD4+ regulatory T cells (Tregs), which inhibit CD8+ T cell activity via direct cytolysis or release of inhibitory cytokines (e.g., TGF-β, IL-10, IL-35), as well as M2-like tumor-associated macrophages (TAMs) and myeloid-derived suppressor cells (MDSCs) (16).