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

Immunoglobulin E (IgE) is a specialized antibody class that plays a central role in the mediation of type I hypersensitivity and allergic inflammatory responses. The Cε3 domain, located within the constant region of the IgE heavy chain, is the specific site responsible for binding to the high-affinity receptor FcεRI on mast cells and basophils, as well as the low-affinity receptor FcεRII (CD23) [PMID: 12446744, UniProt: P01854]. When allergens cross-link IgE molecules bound to these receptors, it triggers the rapid release of inflammatory mediators such as histamine, which leads to the clinical manifestations of asthma and urticaria. Therapeutic strategies targeting the Cε3 domain, most notably the monoclonal antibody Omalizumab, work by binding to free IgE at the same site required for receptor interaction [PubMed: 17017908]. This competitive inhibition prevents IgE from attaching to effector cells, thereby reducing the allergic cascade and downregulating receptor expression over time. Consequently, the Cε3 domain is a validated and highly effective target for managing severe allergic conditions that are poorly controlled by standard therapies [StatPearls: NBK545184].

Other names

IgE CH3 domainCepsilon3 domainImmunoglobulin E constant region domain 3

Monoclonal antibodies bind to the Cε3 domain of circulating IgE, forming small, biologically inactive complexes that prevent IgE from binding to FcεRI on mast cells and basophils, thus inhibiting the release of allergic mediators [PMID: 12446744].