Immunoglobulin heavy constant epsilon CH3 domain (IgE-CH3)

The Immunoglobulin E (IgE) CH3 domain, also known as the Cε3 domain, is a critical structural component of the constant region of the IgE antibody (UniProt: P01854). It plays a central role in the allergic response by serving as the primary binding site for the high-affinity IgE receptor (FcεRI) found on the surface of mast cells and basophils, as well as the low-affinity receptor CD23 (PubMed: 12618897). In sensitized individuals, the binding of allergens to IgE molecules already docked via their CH3 domains to FcεRI triggers the degranulation of these effector cells, leading to the release of inflammatory mediators like histamine and leukotrienes (StatPearls: NBK545184). Therapeutic monoclonal antibodies, most notably Omalizumab, are designed to specifically target the CH3 domain of free, circulating IgE. By masking this domain, these drugs prevent IgE from attaching to its receptors, effectively neutralizing the allergic cascade and leading to a secondary downregulation of FcεRI expression on cell surfaces (NCBI: PMC3539487). Consequently, the CH3 domain is a pivotal therapeutic target for managing IgE-mediated conditions such as moderate-to-severe persistent asthma, chronic spontaneous urticaria, and food allergies (PubMed: 24507034).

Other names

Cε3 domainIgE Fc CH3 domainImmunoglobulin E constant heavy 3 domainIGHE CH3

Binding to the CH3 domain of circulating IgE to sterically hinder its interaction with the high-affinity FcεRI receptor on mast cells and basophils, thereby preventing cellular degranulation and the subsequent allergic cascade (PubMed: 12618897, NCBI: PMC3539487).