Immunoglobulin E and Immunoglobulin G4 (IgE/IgG4)

Allergen-specific Immunoglobulin E (IgE) and Immunoglobulin G4 (IgG4) are critical components of the type I hypersensitivity pathway (Gould & Sutton, 2008, Nature Reviews Immunology). IgE antibodies bind to high-affinity FcεRI receptors on mast cells and basophils; upon allergen cross-linking, these cells release inflammatory mediators like histamine and leukotrienes (UniProt P12319). On B cells, IgE interacts with the low-affinity receptor CD23 (FcεRII) to regulate IgE synthesis and antigen presentation (UniProt P06734). In contrast, IgG4 acts as a "blocking antibody" by competing with IgE for allergen binding and by co-aggregating the inhibitory receptor FcγRIIb on effector cells, thereby dampening the allergic response (Shamji et al., 2011, J Allergy Clin Immunol). Therapeutic interventions such as Allergen Immunotherapy (AIT) aim to shift the immune balance from a Th2-driven IgE response toward a regulatory response characterized by increased IgG4 production. Monoclonal antibodies like Omalizumab specifically target and neutralize free IgE, preventing its binding to receptors and leading to the downregulation of FcεRI on cell surfaces (FDA, Xolair Prescribing Information). Monitoring the ratio of allergen-specific IgE to IgG4 serves as a key biomarker for assessing the efficacy of desensitization treatments in asthma and allergic rhinitis.

Other names

Allergen-specific antibodiesBlocking antibodies (IgG4)Reaginic antibodies (IgE)Type I hypersensitivity antibodiesFc epsilon receptor-associated antibodiesFc gamma receptor-associated antibodies

Neutralization of circulating free IgE to prevent receptor binding, induction of allergen-specific IgG4 blocking antibodies to compete for antigen and engage inhibitory FcγRIIb, and depletion of IgE-switched B cells.