CD8A and neoplasm: Tumor immune microenvironment (TIME) refers to distinct populations of innate and adaptive immune cells, accompanied by different degrees and types of immune cell infiltration (Togo et al., 2020), including mast cells, macrophages, neutrophils, myeloid-derived suppressor cells (MDSCs), B cells, CD4+ T helper (Th) cells, regulatory T cells (Tregs), CD8+ cytotoxic T lymphocytes (CTLs), natural killer (NK) cells, dendritic cells (DCs) and some other innate immune cells.