CD4 and neoplasm: For example, tumor-infiltrating cytotoxic T cells (CD8+) and natural killer (NK) cells have been shown to promote an anti-tumor response [8,9], whereas total CD4+ T cells, regulatory T cells (Treg), and myeloid-derived suppressor cells (MDSCs) are considered pro-tumorigenic and suppress CD8+ T cells and NK cells [8,10].