IL2 and neoplasm: IL-2 released by activated T cells plays a role in NK cell activation and IFNγ production.438,439 Conversely, T helper cell type 1 (Th1) polarization requires IFNγ provided by activated NK cells.440 The same IFN-γ secreted by NK cells will also stimulate IL-12 production by DCs, which activates CD8 + T anti-tumor activity441 (Fig. 7d).