An IL-33 immunotherapy that blocks tumor growth by establishing innate lymphoid cells. (P2084)

Abstract Innate lymphoid cells are recently identified cell population, which produces IL-5, IL-13, and GM-CSF in response to IL-33. These cells play an important role in anti-helminth immunity and allergic diseases. However, little is known about the role of innate lymphoid cells in tumor. We report in this study that sustained intratumoral expression of IL-33 establishes a high numbers of innate lymphoid cells secreting high levels of GM-CSF which are required for inhibition of tumor growth. GM-CSF strongly inhibits proliferation of mural cells (pericytes and smooth muscle cells), thereby preventing normal angiogenesis in tumor mass. Our results identify a previously unrecognized innate immune pathway involving innate lymphoid cells which mediated type-2 innate immunity leading to antitumor activity.