Galactose-α-1,3-galactose epitope (α-Gal)

The α-Gal epitope (galactose-α-1,3-galactose) is a carbohydrate antigen with the canonical structure Galα1–3Galβ1–4GlcNAc that is highly expressed on glycoproteins and glycolipids of non-primate mammals and New World monkeys but not in humans, apes, or Old World monkeys due to inactivation of the α1–3-galactosyltransferase enzyme[3][5][7]. In humans, the immune system produces abundant natural antibodies against the α-Gal epitope, especially IgM, IgG, and IgA, as a result of exposure to gut microbiota and environmental sources[5][7]. In susceptible individuals, repeated tick bites can induce production of IgE antibodies to α-Gal, leading to α-Gal syndrome, a form of delayed anaphylaxis to red meat and mammalian products, and occasionally immediate hypersensitivity to injected or implanted materials containing α-Gal[1][3][5]. The structural similarity to the blood group B antigen means people with blood group B or AB have some protection against developing α-Gal syndrome[8]. The α-Gal epitope is also a significant immunological barrier in xenotransplantation, as natural anti-Gal antibodies in humans rapidly reject transplanted tissue expressing this epitope[4][7].

Other names

α-Gal epitopegalactose-α-1,3-galactosegalactose alpha-1,3-galactoseGalα1-3Galβ1-4GlcNAcalpha-Gal