Hen's egg allergens (Gal d)

Hen's egg allergens are a group of proteins found in chicken eggs that serve as the primary antigens responsible for egg allergy, one of the most prevalent food allergies in children. The most significant allergens are located in the egg white, including ovomucoid (Gal d 1), ovalbumin (Gal d 2), ovotransferrin (Gal d 3), and lysozyme (Gal d 4), while alpha-livetin (Gal d 5) is the major allergen in the yolk [3, 5, 10]. These proteins trigger IgE-mediated type I hypersensitivity by cross-linking specific IgE antibodies on the surface of mast cells and basophils, leading to the rapid release of inflammatory mediators like histamine [9, 14]. This immune activation can result in clinical symptoms ranging from mild skin reactions to life-threatening systemic anaphylaxis [2, 13]. In the context of therapeutic development, these allergens are the targets of immunotherapy (e.g., oral, sublingual, or epicutaneous), where controlled exposure aims to reprogram the immune system toward a state of clinical tolerance [2, 12]. Successful treatment is marked by the induction of regulatory T cells and the production of allergen-specific IgG4 antibodies, which act as competitive inhibitors to prevent IgE-mediated effector cell activation [11, 15].

Other names

Egg allergensHen's egg proteinsGallus gallus allergensEgg white allergensEgg yolk allergensGallus domesticus allergens

Therapeutic strategies targeting egg allergens, such as allergen-specific immunotherapy (AIT), work by inducing immunological desensitization and long-term tolerance. This process involves a shift from a Th2-biased allergic response to a T-regulatory (Treg) and Th1-biased response, characterized by the production of regulatory cytokines like IL-10 and TGF-beta [2, 12]. A central mechanism is the induction of allergen-specific IgG4 'blocking' antibodies, which compete with IgE for allergen binding and interact with the inhibitory receptor FcγRIIb on mast cells and basophils to suppress degranulation and inflammatory mediator release [11, 15, 16].