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

Natural anti-alpha-Gal antibodies (anti-Gal) are some of the most abundant naturally occurring antibodies in humans, constituting approximately 1% of total circulating immunoglobulins. They are produced mainly in the IgG, IgM, IgA, and (in allergy) IgE isotypes in response to continuous exposure to commensal gut microbiota and environmental antigens expressing the α-Gal (galactose-α-1,3-galactose) epitope. Humans, apes, and Old World monkeys lack the enzyme α1,3-galactosyltransferase, so do not express this epitope themselves, instead generating high titers of antibodies against it. Anti-Gal plays significant roles in immunological defense (e.g., as a barrier to some pathogens), but also mediates detrimental responses such as hyperacute xenograft rejection and severe allergic reactions (notably alpha-gal syndrome/meat allergy, mediated by IgE subclass). Anti-Gal antibodies are also implicated in resistance to certain parasitic infections, autoimmune phenomena, and in modulating vaccine and tumor immunogenicity. While widely studied and clinically important, anti-Gal is itself an antibody (not a receptor, enzyme, transporter, or a conventional therapeutic target). Thus, referring to it as a "target" is technically incorrect in the context of therapeutic drug targeting. Anti-Gal is a naturally occurring antibody, not a canonical drug target such as a receptor or enzyme. If the intended target is the α-Gal epitope (galactose-α-1,3-galactose), this would be a more accurate assignment for a molecular target; anti-Gal is a reagent or effector, not a molecule to be targeted directly.

Other names

Anti-GalNatural anti-Gal antibodyAnti-α-Gal antibodyAnti-galactose-α-1,3-galactose antibodyAnti-Gal IgGAnti-Gal IgMAnti-Gal IgAAnti-Gal IgE

Cetuximab: Severe allergic reactions occur in patients with anti-Gal IgE as the drug contains the α-Gal epitope, leading to IgE-mediated mast cell/basophil activation.