Abstract 4731: Contribution of FcγRIIB to creating the suppressive tumor microenvironment

Various immune cells are recruited in tumor microenvironment. It is well established that cellular immune responses, such as cytotoxic or suppressive activities play an important role in regulating tumor growth and metastasis. However, contribution of humoral immune responses against tumor is incompletely understood. The Fc receptors constitute critical elements for activating or down-regulating immune responses through immunoglobulin immune complex. Here, we examined the potential role of inhibitory Fc receptor, Fc gamma RIIb in tumor immunity using mice model. Current findings indicate that tumor-specific antibodies are induced and control tumor immunity. Deletion of Fc gamma RIIb receptor significantly improves both cellular and humoral anti-tumor immunity, delays tumor growth. These findings indicate that spontaneous antibody against tumor create the suppressive tumor microenvironment through Fc gamma RIIb signaling, and suggests attractive therapeutic target for cancer immunotherapy. Citation Format: Yuki Kasahara, Hidekazu Shirota, Chikashi Ishioka. Contribution of FcγRIIB to creating the suppressive tumor microenvironment [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4731.