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

The Galactose-alpha-1,3-galactose epitope (α-Gal epitope) is a carbohydrate antigen with the structure Galα1–3Galβ1–4GlcNAc–R, found on glycoproteins and glycolipids of most mammals except humans, apes, and Old World monkeys, who lack the enzyme α-1,3-galactosyltransferase (GGTA1) that synthesizes it[1][3][7]. In these primates, exposure to α-Gal, via food, biologicals, or tick bites, leads to production of anti-α-Gal antibodies of several classes (especially IgE and IgG), underlying the basis for α-Gal syndrome (red meat allergy)[2][3][5]. The same epitope also causes strong immune rejection of animal tissues in xenotransplantation, and its immunologic distinctness from human blood group antigens explains its potent immunogenicity[4][5][7]. The α-Gal epitope may also contribute to human defense against α-Gal-expressing parasites, including Trypanosoma cruzi and Leishmania species[4]. Detection of specific anti-α-Gal IgE acts as a biomarker for diagnosis of α-Gal syndrome, while presence of the epitope on certain therapeutics (notably cetuximab) is associated with risk of immediate hypersensitivity reactions[2].

Other names

alpha-Gal epitopeα-GalGalili antigenGalα1–3GalGalα1–3Galβ1–4GlcNAc–RGalactose-α-1,3-galactose

Elicitation of IgE-mediated anaphylaxis and delayed allergic reactions; Induction of antibody-mediated rejection of animal tissues in transplants.