Intratumorally Establishing Type 2 Innate Lymphoid Cells Blocks Tumor Growth.

A long-standing question in the field of tumor immunotherapy is how Th2 cytokines block tumor growth. Their antitumor effects are particularly prominent when they are secreted continuously in tumors, suggesting that Th2 cytokines may create a tumor microenvironment unfavorable for tumor growth independently of adaptive immunity. In this study, we show that local production of IL-33 establishes a high number of type 2 innate lymphoid cells (ILC2s) with potent antitumor activity. IL-33 promotes secretion of a massive amount of CXCR2 ligands from ILC2s but creates a tumor microenvironment where tumor cells express CXCR2 through a dysfunctional angiogenesis/hypoxia/reactive oxygen species axis. These two signaling events converge to reinforce tumor cell-specific apoptosis through CXCR2. Our results identify a previously unrecognized antitumor therapeutic pathway wherein ILC2s play a central role.