CD79ab

CD79ab is a complex of two closely associated transmembrane proteins, CD79a (also known as Igα) and CD79b (Igβ), that play a critical role in B cell receptor (BCR) signaling. These proteins are essential components of the B cell antigen receptor complex, which mediates the immune response to pathogens by recognizing and binding specific antigens.

CD79a and CD79b are encoded by the MS4A1 and MS4A2 genes, respectively, both located on chromosome 19 in humans. Each protein contains an extracellular immunoglobulin-like domain, a transmembrane region, and an intracellular tail. The extracellular domains interact with the membrane-proximal constant region of the B cell receptor’s immunoglobulin heavy and light chains, forming a stable complex. The intracellular tails lack intrinsic enzymatic activity but associate with other signaling molecules, such as Lyn, Syk, and BLNK, to initiate downstream signaling cascades upon antigen binding.

Activation of the CD79ab complex triggers a series of phosphorylation events that lead to B cell activation, proliferation, differentiation, and antibody production. Mutations or defects in CD79ab can impair BCR signaling, leading to immunodeficiency or autoimmune disorders. For example, loss-of-function mutations in MS4A1 or MS4A2 have been linked to conditions such as common variable immunodeficiency (CVID) or increased susceptibility to infections.

CD79ab is also a target for therapeutic intervention in certain B cell malignancies, such as chronic lymphocytic leukemia (CLL), where it is overexpressed. Antibody-based therapies, such as ibrutinib and other small-molecule inhibitors, disrupt CD79ab signaling pathways to inhibit tumor growth.

Research on CD79ab continues to elucidate its role in B cell development, immune regulation, and disease pathogenesis, offering potential avenues for novel immunotherapies.