B-lymphocyte antigen CD79b (CD79b)

B-lymphocyte antigen CD79b is a transmembrane protein that forms a critical part of the B-cell receptor (BCR) complex, associating non-covalently with immunoglobulin and CD79a (Igα) on the surface of B cells. CD79b is mainly expressed on B cells from the pre-B cell stage through mature B-cell development—and is largely absent just before the final differentiation to plasma cells. The extracellular domain participates in immunoglobulin binding, while the cytoplasmic domain contains immunoreceptor tyrosine-based activation motifs (ITAMs), essential for downstream signaling upon receptor activation. Activation of the BCR, and hence CD79b, triggers intracellular signaling that regulates B-cell activation, proliferation, differentiation, internalization of the antigen-receptor complex, and antigen presentation to T cells. CD79b surface expression is highly restricted to B cells and B-cell neoplasms, making it a valuable therapeutic target, notably for antibody-drug conjugates like polatuzumab vedotin in B-cell lymphomas. Mutations or aberrant expression of CD79b have roles in immunodeficiency syndromes and are frequently found in certain B-cell cancers. Major therapeutic challenges include the risk of normal B-cell depletion and consequent immunosuppression, as well as tumor heterogeneity in CD79b expression.

Other names

CD79BIgbetaB29immunoglobulin-associated betaAGM6CD79b moleculeimmunoglobulin-associated B29 protein

Antibody-drug conjugate binding to CD79b induces internalization and delivers cytotoxin to B-cell lymphoma cells, resulting in cell death; Inhibition of BCR-mediated signaling pathways (via anti-CD79b monoclonal antibodies)