IL4 and neoplasm: Finally, we found that approximately half of the IL-21+CD4+ T cells in the tumor tissues were IFN-γ positive (45.6 ± 5.2%) and that IL-21+CD4+ T cells were rarely IL-4 (0.8 ± 0.3%) or IL-17 (1.6 ± 0.5%) positive (Figures 1E, F).