ABO blood group A antigen (A antigen)

The ABO blood group A antigen is a terminal carbohydrate structure found on the surface of red blood cells, as well as various epithelial and endothelial cells throughout the body [4, 13]. It is synthesized by the ABO glycosyltransferase (A-transferase), which adds an N-acetylgalactosamine (GalNAc) residue to the H antigen precursor [7, 14]. Biologically, the A antigen plays a role in cell-cell recognition and serves as a receptor for various pathogens, including certain strains of bacteria and viruses [5, 8]. In clinical medicine, it is a primary target of naturally occurring anti-A antibodies, making it a critical factor in transfusion compatibility and organ transplantation [12, 13]. Incompatibility can lead to severe immune responses, such as acute hemolytic transfusion reactions or hyperacute organ rejection [13, 14]. Furthermore, the A antigen is being investigated as a target for novel cancer immunotherapies, where its expression on tumor cells can be used to trigger complement-mediated lysis by endogenous antibodies [1, 2, 3].

Other names

Blood group A antigenHisto-blood group A antigenA substanceGalNAc-alpha-1,3-(Fuc-alpha-1,2)-Gal-beta-1,3/4-GlcNAcBlood group A substance

Antibody-mediated complement activation and enzymatic cleavage of terminal sugar residues