Natural anti-Gal antibodies (Anti-Gal)

Natural anti-Gal antibodies are the most abundant naturally occurring antibodies in humans, constituting approximately 1% of circulating immunoglobulins (Galili, 2013 [1]). These antibodies specifically target the alpha-gal epitope (Galα1-3Galβ1-4GlcNAc-R), a carbohydrate structure found on the cells of non-primate mammals but absent in humans, apes, and Old World monkeys due to the evolutionary loss of the GGTA1 gene (Cooper et al., 2015 [2]). In the context of xenotransplantation, anti-Gal antibodies are the primary mediators of hyperacute rejection, as they bind to alpha-gal antigens on porcine organ grafts and activate the complement cascade (Galili, 2013 [1]). Beyond rejection, these antibodies are being exploited in cancer immunotherapy to tag tumor cells with alpha-gal epitopes, thereby recruiting the patient's own anti-Gal antibodies to destroy the tumor (Galili, 2023 [3]). They also function as a potent immunological adjuvant by enhancing the uptake of alpha-gal-coated antigens by antigen-presenting cells. However, the development of IgE-class anti-Gal antibodies, often triggered by tick bites, leads to alpha-gal syndrome, a serious delayed allergic reaction to mammalian meat (Commins et al., 2011 [4]).

Other names

Anti-alpha-galactosyl antibodiesAnti-Gal antibodiesAnti-alpha-gal antibodiesAnti-Galα1-3Gal antibodies

Anti-Gal antibodies are targeted through several mechanisms: depletion using soluble alpha-gal mimetics (e.g., GAS914) to prevent xenograft rejection; recruitment to tumor cells via alpha-gal functionalization to induce immune-mediated destruction; and utilization as an adjuvant to facilitate antigen uptake by antigen-presenting cells through Fc-gamma receptor-mediated endocytosis (Galili, 2013 [1]; Galili, 2023 [3]).