Anti-CD16 Antibody, mAb

CD16 (FcγRIII), a low-affinity receptor for the Fc region of IgG antibodies, exists in two primary isoforms: CD16a (FcγRIIIa) and CD16b (FcγRIIIb). CD16a is primarily expressed on natural killer (NK) cells, macrophages, and a subset of T cells, where it serves as a critical marker for NK cell identification and function. It plays an essential role in antibody-dependent cellular cytotoxicity (ADCC) by recognizing IgG-opsonized target cells, thereby triggering cytotoxic responses against tumors and infected cells. Studies have shown that enhanced CD16a expression significantly strengthens the tumor-killing capacity of immune effector cells, as observed in gastric cancer, hepatocellular carcinoma, and chronic lymphocytic leukemia.

In contrast, CD16b (FcγRIIIb) is a glycosylphosphatidylinositol (GPI)-anchored protein expressed predominantly on neutrophils and activated eosinophils. While it also binds immune complexes, its role is more associated with the regulation of neutrophil activation, phagocytosis, and inflammatory responses rather than direct cytotoxicity. Both isoforms are vital in bridging innate and adaptive immunity, making CD16 an important target in immunotherapy, particularly in the development of monoclonal antibodies and engineered immune cells aimed at enhancing anti-tumor activity.