Immunoglobulin heavy constant epsilon Cε3 domain (IgE Cε3)

The Cε3 domain of human Immunoglobulin E (IgE) is a pivotal structural segment within the Fc region of the IgE molecule [1.2.1]. It serves as the essential docking site for the high-affinity IgE receptor (FcεRI) found on mast cells and basophils, as well as the low-affinity receptor (CD23/FcεRII) on B cells [1.2.2]. In allergic diseases, free circulating IgE binds to these receptors via the Cε3 domain, sensitizing the immune system to specific allergens [1.2.3]. Upon subsequent allergen exposure, the cross-linking of these IgE-receptor complexes triggers the rapid release of inflammatory mediators, such as histamine and leukotrienes [1.2.4]. These mediators drive the clinical symptoms of conditions like allergic asthma, chronic spontaneous urticaria, and anaphylaxis [1.4.3]. Therapeutic agents like Omalizumab specifically target the Cε3 domain of free circulating IgE to prevent its interaction with receptors [1.3.2]. This binding neutralizes the allergic response and leads to a secondary downregulation of FcεRI density on effector cells [1.3.1]. The Cε3 domain is thus a validated and highly effective target for managing moderate-to-severe IgE-mediated allergic disorders [1.4.1].

Other names

CH3 domain of IgEC-epsilon-3 domainIGHE Cε3Fcε3 domainHuman IgE Cε3

Neutralization of free circulating IgE by binding to the Cε3 domain, which competitively inhibits interaction with FcεRI and CD23 receptors, leading to reduced mast cell/basophil activation and downregulation of surface receptor expression.