Immunoglobulin heavy constant epsilon 3 domain (IgE Cε3) (IgE Cε3)

The Immunoglobulin E (IgE) Cε3 domain is a pivotal structural segment of the IgE heavy chain constant region, playing a central role in the mediation of allergic responses (UniProt P01854). It serves as the primary docking site for the high-affinity IgE receptor (FcεRI) located on mast cells and basophils, as well as the low-affinity receptor (CD23/FcεRII) (PMID: 12165515). Interaction between the Cε3 domain and FcεRI is essential for the sensitization of these immune cells; subsequent allergen exposure leads to IgE cross-linking and the release of potent inflammatory mediators like histamine. In diseases such as allergic asthma and chronic spontaneous urticaria, the overproduction of IgE and its binding via the Cε3 domain drive chronic inflammation and hypersensitivity. Therapeutic strategies, most notably the monoclonal antibody Omalizumab, specifically target the Cε3 domain to sterically hinder its interaction with FcεRI (PMID: 25130604). This binding not only neutralizes circulating IgE but also leads to the downregulation of FcεRI receptors on the surface of effector cells, providing a dual mechanism for reducing allergic sensitivity. Consequently, the Cε3 domain is a validated and highly effective pharmacological target for managing severe IgE-mediated disorders.

Other names

CH3 domain of IgECepsilon3 domainIgE-Fc Cε3 domainCε3 domainImmunoglobulin heavy constant epsilon domain 3

Monoclonal antibodies bind to the Cε3 domain of circulating IgE, sterically inhibiting its interaction with the high-affinity FcεRI receptor on mast cells and basophils, which prevents the release of inflammatory mediators and downregulates receptor expression (PMID: 25130604).