CD4 and neoplasm: Tumor tissues are infiltrated by immunosuppressive cells such as regulatory T cells and myeloid-derived suppressor cells, and M2-polarized TAMs, which produce inhibitors such as PD-1/PD-L1, lymphocyte activation gene-3, IL-10, and TGF-β, inhibit the proliferation of CD4, CD8 cells, and their immune response (Han et al., 2019; Liu et al., 2019; Yu et al., 2019).