Human anti-alpha-galactosyl antibodies (Anti-Gal)

Human anti-alpha-galactosyl (anti-Gal) antibodies are naturally occurring antibodies that constitute approximately 1% of circulating immunoglobulins in humans, apes, and Old World monkeys (Galili, 2013, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3724437/). These antibodies specifically target the alpha-gal epitope (Gal-alpha-1,3-Gal-beta-1,4-GlcNAc-R), a carbohydrate structure absent in humans due to the evolutionary inactivation of the alpha-1,3-galactosyltransferase gene. Anti-Gal antibodies are primarily responsible for the hyperacute rejection of porcine xenografts, as they bind to alpha-gal epitopes on the graft endothelium and trigger rapid complement-mediated lysis. Additionally, they mediate alpha-gal syndrome, a unique IgE-mediated food allergy to red meat triggered by tick bites (Commins et al., 2011, https://doi.org/10.1016/j.jaci.2011.02.019). In therapeutic contexts, these antibodies are being harnessed for cancer vaccines to enhance the immunogenicity of tumor cells or are targeted for depletion to facilitate successful xenotransplantation.

Other names

Anti-Gal antibodiesAnti-alpha-galactosyl IgGAnti-alpha-galactosyl IgMAnti-alpha-galactosyl IgAAnti-alpha-galactosyl IgEAntibodies to Gal-alpha-1,3-Gal

Therapeutic strategies involve the depletion of anti-Gal antibodies via immunoadsorption columns, the use of soluble alpha-gal mimetics to competitively inhibit antibody binding to xenografts, or the enzymatic removal of alpha-gal epitopes from donor tissues. In oncology, alpha-gal epitopes are engineered onto tumor cells to recruit anti-Gal antibodies, which then trigger complement-mediated lysis and enhance tumor antigen presentation to T cells (Galili, 2023, https://doi.org/10.3390/biom13081252).