CD4 and neoplasm: Furthermore, IL-2, IL-12, IFN-γ and TNF-α have been reported to stimulate CD4+ Th1 differentiation and accelerate Th1-mediated antitumor responses [31,32]; In addition, these cytokines stimulate CD8+ cytotoxic T lymphocytes (CTLs), the most important effector cells that recognize and eliminate tumor cells [33].