Human B cell receptor (BCR) (BCR)

The Human B cell receptor (BCR) is a multi-subunit transmembrane complex found on the surface of B lymphocytes, consisting of an antigen-binding immunoglobulin (mIg) and a signaling heterodimer of CD79A and CD79B (UniProt P04234, P40259). The paratope is the specific region within the variable domains of the BCR that recognizes and binds to a particular antigen epitope with high affinity (Janeway's Immunobiology, 2001). This interaction is the primary event in B cell activation, triggering intracellular signaling cascades that lead to cell proliferation, differentiation, and the production of secreted antibodies (StatPearls, 2023). In B-cell malignancies, the BCR often remains constitutively active or provides essential survival signals, making it a critical therapeutic target (PubMed PMC4112144). Because each B-cell clone expresses a unique BCR idiotype, the paratope can be targeted with high specificity using anti-idiotype antibodies or personalized vaccines to treat lymphomas without affecting the broader B-cell population (PubMed PMC1904831). Additionally, components of the BCR complex, such as CD79B, are targeted by antibody-drug conjugates like polatuzumab vedotin to deliver cytotoxic agents directly to malignant B cells (FDA Label, 2019). Therapeutic modulation of the BCR is also explored in autoimmune diseases to suppress pathogenic B-cell responses (PubMed PMC6433481).

Other names

B-lymphocyte antigen receptorSurface immunoglobulinsIgIdiotypeAntigen-binding siteParatope

Binding to the BCR complex (e.g., CD79B) to deliver cytotoxic payloads or binding to the unique paratope (idiotype) to induce targeted immune-mediated destruction of specific B-cell clones (FDA Label, 2019; PubMed PMC1904831).