CD8A and neoplasm: During tumor growth, TILs such as NK cells and CD8+T cells (cytotoxic T lymphocyte, CTL) are responsible for tumor killing, while some cells inhibit tumor immunity, including CD4+ regulatory T cells (Treg, the main composition of tumor CD4+T cells), myeloid-derived uppressor cells (MDSC) and tumor-associated macrophages (TAM) [14,15].