High-affinity immunoglobulin epsilon receptor I-bound immunoglobulin E (FcεRI-bound IgE)

The FcεRI-bound IgE complex is a molecular assembly consisting of Immunoglobulin E (IgE) antibodies tethered to the high-affinity IgE receptor (FcεRI) on the surface of mast cells and basophils (UniProt P12319). This complex is the central mediator of the allergic cascade; when allergens cross-link these pre-bound IgE molecules, they trigger the release of inflammatory mediators like histamine, leading to symptoms of asthma, allergic rhinitis, and anaphylaxis (StatPearls, 2023). While established therapies like omalizumab (Xolair) effectively sequester free serum IgE to prevent new complexes from forming, they are unable to bind to IgE that is already attached to the receptor due to steric hindrance (NCBI, 2022). Consequently, the FcεRI-bound IgE complex has become a focal point for the development of "IgE disruptors," such as DARPins and high-affinity antibodies, which are designed to actively dissociate IgE from its receptor (Nature Communications, 2017). Targeting this specific state is crucial for achieving rapid desensitization in patients with high baseline IgE levels or severe chronic spontaneous urticaria, where the persistence of receptor-bound IgE maintains disease activity.

Other names

IgE-FcεRI complexReceptor-bound IgEMast cell-bound IgEBasophil-bound IgESurface-bound IgE

Active dissociation of IgE from the FcεRI receptor and prevention of allergen-mediated cross-linking.