Murine CD27(-) Vγ6(+) γδ T cells producing IL-17A promote ovarian cancer growth via mobilization of protumor small peritoneal macrophages

Tumor development is impacted by a set of diverse infiltrating leukocyte populations that can either inhibit or, paradoxically, enhance tumor cell growth. This study characterizes a cellular cross-talk between γδ T lymphocytes and small peritoneal macrophages (SPMs) that is mediated by the proinflammatory cytokine, IL-17, and promotes ovarian cancer growth. IL-17 is preferentially produced by a population of γδ T cells, displaying a distinctive CD27^(-) Vγ6⁽⁺⁾ phenotype, that strongly proliferate in response to tumor challenge. This associates with the mobilization of SPMs that express protumor and proangiogenic molecular mediators upregulated by IL-17. Critically, these SPMs can directly enhance ovarian cancer cell growth. Our work identifies an IL-17-dependent γδ T cell/SPM axis that promotes tumor development and thus counteracts cancer immunosurveillance.