Natural human anti-Gal antibody (Anti-Gal) (Anti-Gal)

The natural human anti-Gal antibody is the most abundant naturally occurring antibody in humans, constituting approximately 1% of circulating immunoglobulins (IgG, IgM, and IgA) (Galili, 2013). It specifically recognizes the alpha-gal epitope (Galα1-3Galβ1-4GlcNAc-R), a carbohydrate structure present on the cells of non-primate mammals but absent in humans, apes, and Old World monkeys due to the evolutionary inactivation of the alpha-1,3-galactosyltransferase gene (Galili, 2005). This antibody plays a pivotal role in xenotransplantation, where it serves as the primary mediator of hyperacute rejection by binding to alpha-gal epitopes on donor animal tissues and activating the complement cascade. Beyond its role in rejection, anti-Gal is being therapeutically harnessed in 'alpha-gal therapy' to enhance the immunogenicity of vaccines and accelerate wound healing. By decorating vaccines or damaged tissues with alpha-gal epitopes, the antibody can be recruited to promote opsonization, recruitment of antigen-presenting cells, and localized inflammatory responses that favor tissue repair or immune activation (Galili, 2020). Additionally, the antibody is central to alpha-gal syndrome, a delayed allergic reaction to red meat induced by tick bites that sensitize individuals to the epitope (Commins et al., 2011).

Other names

Anti-alpha-galactosyl antibodyAnti-alpha-GalAnti-Gal IgGAnti-Gal IgMAnti-Gal IgANatural anti-Gal antibody

The antibody binds specifically to the alpha-gal epitope (Galα1-3Galβ1-4GlcNAc-R). In the context of xenotransplantation, this binding triggers the classical complement pathway, leading to hyperacute rejection of the graft (Galili, 2013). In therapeutic vaccine contexts, the antibody opsonizes alpha-gal-coated antigens, promoting their uptake by professional antigen-presenting cells via Fc-gamma receptors (FcγR), which enhances the subsequent T-cell mediated immune response (Galili, 2020).