CD4 and neoplasm: Among the anti-tumor cytokines, TNF-α and IL-12 p70 are chiefly secreted by macrophages – the former has a direct, strong tumoricidal effect and the latter is key to activating anti-tumor T cells; while IFN-γ, abundantly produced by CD4 (Th1) and CD8 cytotoxic T lymphocytes (CTLs), plays an essential role in establishing tumor immunosurveillance.