CD8A and neoplasm: For example, Tregs could secrete immunosuppressive cytokines such as TGF-β, IL-10, and IL-35 (Sullivan et al., 2020); inhibit antigen presentation functions of dendritic cells and CD4 + T helper cells; and generate tumor-specific CD8 + cytotoxic T lymphocytes (CTLs), which act as barriers of anti-tumor immune response and result in the motivation of tumor immune escape.