CD4 and neoplasm: The tumor-infiltrating leukocytes include both proinflammatory immune cells, such as dendritic cells (DC), cytotoxic CD8+ T cells (CTL), CD4+ T helper cells (TH), and natural killer cells (NK), as well as immunosuppressive immune cells like tumor-associated macrophages (TAM), regulatory T cells (TREG), myeloid derived suppressor cells (MDSC), and tumor-associated neutrophils (TAN), negatively regulating tumor immunity.