CD8A and neoplasm: Tumor-infiltrating immune cells include NK cells, monocytes, CD8+ cytotoxic (memory) T cells, CD4+ helper (Th1, Th2) T cells, regulatory T cell (Treg), B-cells, tumor-associated macrophages (TAMs), tumor-associated neutrophils (TANs), myeloid-derived suppressor cells (MDSCs), DCs, and NK cells [66,67,68].