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

The Galactose-alpha-1,3-galactose (α-gal) epitope is a carbohydrate structure found on the glycoproteins and glycolipids of non-primate mammals and New World monkeys, but it is notably absent in humans, apes, and Old World monkeys due to the evolutionary inactivation of the GGTA1 gene (Galili, U., 2013, Immunology and Cell Biology). Humans naturally possess high titers of anti-α-gal antibodies (Anti-Gal), which constitute approximately 1% of circulating immunoglobulins, resulting from continuous exposure to α-gal-like structures on gut microbiota (Machado et al., 2021, Journal of Clinical Medicine). In the context of 'HyperAcute' immunotherapy, such as the HyperAcute Renal (NLG-0101) vaccine, allogeneic renal cancer cells are genetically modified to express the α-gal epitope on their surface (Whalen et al., 2012, Journal of Clinical Oncology). Upon administration, the patient's natural anti-Gal antibodies bind to these epitopes, initiating a rapid immune response through complement activation and antibody-dependent cellular cytotoxicity. This process promotes the recruitment of professional antigen-presenting cells to the site, which then process and present tumor-associated antigens to the adaptive immune system, potentially inducing a systemic T-cell-mediated attack on the patient's own tumor cells. Beyond its use in oncology, the α-gal epitope is the primary barrier to successful xenotransplantation, as it triggers hyperacute rejection of porcine organs, and it is also the allergen responsible for alpha-gal syndrome, a tick-borne allergy to red meat.

Other names

Alpha-galGalalpha1-3GalGal-alpha-1,3-GalXenotransplantation antigenGGTA1 productHyperAcute Renal vaccine antigen

Binding of natural anti-Gal antibodies to the α-gal epitope on engineered cells triggers complement-mediated lysis and opsonization, leading to enhanced antigen presentation and a systemic T-cell response against tumor-associated antigens.