B blood group antigen (B antigen)

The B blood group antigen is a terminal carbohydrate structure expressed on the surface of red blood cells, vascular endothelium, and various epithelial cells (Dean, 2005). It is synthesized by the action of the B-allele-encoded alpha-1,3-galactosyltransferase, which adds a terminal galactose residue to the H antigen precursor (NCBI, 2023). In clinical medicine, the B antigen is a critical barrier in blood transfusion and organ transplantation, as individuals lacking the antigen possess naturally occurring anti-B antibodies that trigger life-threatening immune responses upon exposure (StatPearls, 2023). Therapeutic strategies targeting the B antigen primarily focus on enzymatic conversion, using specific alpha-galactosidases to strip the terminal sugar and transform Type B red cells into universal Type O cells (Rahfeld & Withers, 2020). Additionally, the B antigen serves as a receptor for certain pathogens and is associated with varying risks for cardiovascular and infectious diseases (Liumbruno & Shaz, 2012). The antigen is also a target for immunoabsorption therapies designed to remove circulating anti-B antibodies in patients undergoing ABO-incompatible organ transplants (Takahashi, 2005).

Other names

Blood group B antigenABO B antigenType B blood group antigenB substanceGal-alpha-1,3-(Fuc-alpha-1,2)-Gal

Enzymatic cleavage of the terminal alpha-1,3-galactose residue to convert the B antigen into the H antigen (Type O blood) or antibody-mediated binding for diagnostic detection and immune clearance.