FcγRIIB receptors were demonstrated to promote the internalization of rituximab and thereby inhibit macrophage-dependent phagocytosis of malignant B cells in chronic lymphocytic leukemia (CLL) and mantle cell leukemia.68 An antagonistic human FcγRIIB antibody was found to be effective in mice xenografts of primary, as well as CD20-refractory CLL.69 This effect was mediated, in part by preventing the internalization of rituximab from the surface of malignant cells, and in part by direct cytotoxicity.69 Here, FCGR2B is linked to B-cell chronic lymphocytic leukemia.