ABO blood group system antigens (ABO antigens)

The ABO blood group system antigens are complex carbohydrate structures (oligosaccharides) found on the surface of red blood cells, as well as on various other tissues and in secretions. These antigens are synthesized by specific glycosyltransferases that append terminal sugar residues—N-acetylgalactosamine for the A antigen and D-galactose for the B antigen—to a precursor H antigen (StatPearls, NBK2267). They are of paramount importance in transfusion medicine and organ transplantation, as the presence of naturally occurring antibodies (isohemagglutinins) against non-self ABO antigens can trigger catastrophic immune-mediated hemolysis or hyperacute organ rejection (NIH, Blood Groups and Red Cell Antigens). Beyond their immunological role, ABO antigens are associated with the regulation of von Willebrand factor levels and contribute to the pathogenesis of cardiovascular diseases, certain infections, and gastric cancers (Blood, 2019). Therapeutic interventions targeting these antigens include the use of recombinant glycosidases to convert blood types for universal transfusion and the application of desensitization protocols, such as plasmapheresis and B-cell depletion, to enable ABO-incompatible transplants (Nature Microbiology, 2019).

Other names

A antigenB antigenH antigenABO blood group substancesBlood group A/B/OH substance

Enzymatic removal of terminal immunodominant sugar residues (N-acetylgalactosamine for A, galactose for B) to convert antigens to the universal H antigen (Type O); or therapeutic depletion of anti-ABO antibodies and B-cells to prevent immune-mediated destruction of cells or organs expressing these antigens.