Metastatic Melanomas Express Inhibitory Low Affinity Fc Gamma Receptor and Escape Humoral Immunity

Figure 2

Tumor FcγRIIB1 expression protects metastatic melanoma from ADCC. Metastatic melanomas that express the FcγRIIB1 are resistant in vitro and in vivo in immunocompetent mice to the ADCC mediated by FcR γ chain dependent effector cells (NK cells, neutrophiles monocytes, or macrophages). The tumor FcγRIIB1 are decoy receptors. The Fc portions of anti-tumor antibodies are captured by the tumor FcγRIIB1 and cannot interact with the Fcγ of the immune effector cells.