FCGR2B and neoplasm: We determined the infiltration of these immunosuppressive cells into the TME, and found that MDSC accumulation was reduced in the tumor and spleen of MC38 tumor-bearing FcγRIIB-KO mice than in that of tumor-bearing WT mice (Figures 2E, 2F, and S2D-H), whereas there was no significant difference in the levels of Treg cells, B cells, and DCs (Figures S2D-E).