Allergen-specific immunoglobulin G (sIgG)

Allergen-specific immunoglobulin G (IgG), particularly the IgG4 subclass, is a critical component of the immune system's ability to develop tolerance toward environmental and food allergens. In allergic individuals, exposure to allergens typically triggers a Th2-mediated response characterized by high levels of allergen-specific IgE, which sensitizes mast cells and basophils. Therapeutic interventions like allergen immunotherapy (AIT) aim to shift this balance by inducing the production of allergen-specific IgG. These antibodies function as blocking antibodies by competing with IgE for allergen binding, thus preventing the cross-linking of IgE receptors and the subsequent release of inflammatory mediators like histamine (Akdis & Akdis, 2014; Shamji & Durham, 2017). Furthermore, allergen-specific IgG can engage the inhibitory receptor FcγRIIb on the surface of effector cells, providing a potent negative signal that suppresses allergic inflammation (NIH/NIAID). Consequently, the induction of allergen-specific IgG4 is widely recognized as a key immunological marker of successful desensitization and long-term clinical efficacy in treating allergic rhinitis, asthma, and life-threatening food or venom allergies.

Other names

Allergen-specific IgGBlocking antibodyAntigen-specific IgGAllergen-specific IgG4sIgG4

Allergen-specific IgG acts as a blocking antibody that competitively inhibits the binding of allergens to IgE on mast cells and basophils, thereby preventing degranulation. It also facilitates the co-aggregation of the inhibitory receptor FcγRIIb with the high-affinity IgE receptor FcεRI, leading to the inhibition of downstream pro-inflammatory signaling (Akdis & Akdis, 2014; Shamji & Durham, 2017).