Galactose-alpha-1,3-galactose-beta-1,4-N-acetylglucosamine (Alpha-gal epitope) (Alpha-gal)

Galactose-alpha-1,3-galactose-beta-1,4-N-acetylglucosamine, commonly known as the alpha-gal epitope, is a carbohydrate antigen expressed on the cell surfaces of most mammals, excluding humans, apes, and Old World monkeys [PMID: 11485738]. In these primates, the gene encoding the enzyme alpha-1,3-galactosyltransferase (GGTA1) is inactivated, leading to the production of high titers of natural anti-Gal antibodies [PMID: 23433487]. This epitope is the primary mediator of hyperacute rejection in xenotransplantation, as human antibodies bind to the glycan on donor animal tissues and trigger the complement cascade [PMID: 8383531]. Additionally, sensitization to alpha-gal via tick bites can lead to alpha-gal syndrome, a delayed allergic reaction to red meat [PMID: 19062471]. Therapeutic strategies involve the use of alpha-galactosidase enzymes to strip the epitope from tissues or the development of genetically modified donor animals (GGTA1 knockouts) to eliminate its expression [PMID: 11742396].

Other names

Gal-alpha-1,3-GalAlpha-gal epitopeGalili antigenGal-alpha-1,3-Gal-beta-1,4-GlcNAcXenoantigen

Enzymatic cleavage of the terminal alpha-galactose residue or competitive inhibition of anti-Gal antibodies to prevent complement-mediated cell lysis [PMID: 11742396].