CD4 and neoplasm: On the other hand, Th1 exert an anti-tumor immune response by secreting cytokines such as TNF-α and IL-2, and in contrast to Th1, Th2 can suppress the immune system and promote tumor progression [15].Besides, Naive CD4+ T cells differentiate into Th17 cells in the presence of IL-6 and TGF-β, and convert into Treg cells in the presence of IL-2 and TGF-β [16, 17].