Endogenous anti-alpha-galactosyl antibody (Anti-Gal)

Endogenous anti-alpha-galactosyl (anti-Gal) antibodies are naturally occurring immunoglobulins found in humans, apes, and Old World monkeys, constituting approximately 1% of circulating IgG (Galili, 2005, Immunol Cell Biol). These antibodies specifically target the alpha-gal epitope (Galα1-3Galβ1-4GlcNAc-R), a carbohydrate structure synthesized by the enzyme alpha-1,3-galactosyltransferase in most mammals but absent in humans due to the evolutionary inactivation of the GGTA1 gene (Cooper et al., 2008, Front Biosci). In clinical medicine, anti-Gal antibodies are the primary cause of hyperacute rejection in xenotransplantation, as they bind to the alpha-gal epitopes on donor animal tissues and activate the complement system (Galili, 2013, Xenotransplantation). They also play a central role in Alpha-gal syndrome, a tick-bite-associated allergy where IgE antibodies against alpha-gal cause delayed anaphylaxis after consuming red meat or receiving drugs like cetuximab that contain the epitope (Commins et al., 2011, J Allergy Clin Immunol; Chung et al., 2008, N Engl J Med). Conversely, therapeutic strategies are being developed to functionalize tumor cells with alpha-gal epitopes to recruit these abundant endogenous antibodies for targeted cancer immunotherapy via antibody-dependent cellular cytotoxicity (Galili, 2023, Antibodies).

Other names

Anti-Gal antibodyAnti-alpha-gal antibodyNatural anti-Gal antibodiesAnti-alpha-1,3-galactosyl antibodiesAnti-alpha-galactosyl IgGAnti-alpha-galactosyl IgM

Binding to alpha-gal epitopes on foreign cells or therapeutic proteins to induce complement-mediated lysis and ADCC, or sequestration/depletion of the antibody to prevent xenograft rejection.