In human bladder cancer, intra-tumoral cytotoxic CD4+ T lymphocytes, rather than canonical CD8+ T lymphocytes, mediate anti-cancer immunity (14); CD4+T cells could also exert their anti-tumor immunity by secretion of IFN-γ and TNF for recruitment of effector immune cells and the induction of tumor senescence (15, 16). Here, CD4 is linked to cancer.