Immunoglobulin E antibody–high-affinity Fc epsilon RI receptor complex (IgE–FcεRI complex)

IgE is an antibody class central to type I hypersensitivity reactions. FcεRI is its high-affinity receptor, expressed primarily as a heterotetramer (αβγ2) on mast cells and basophils, and as a trimer (αγ2) on human antigen-presenting cells. The complex forms when IgE’s Fc region binds to FcεRI’s α-chain. Upon allergen exposure, cross-linking of IgE–FcεRI complexes on cell surfaces triggers signaling cascades, leading to rapid release of mediators like histamine, causing allergic symptoms and, in severe cases, anaphylaxis. This interaction is the canonical molecular trigger for immediate allergic reactions. FcεRI function and IgE binding are major therapeutic targets in the management of allergic diseases; anti-IgE therapies (e.g., omalizumab) disrupt this pathway to prevent cell activation and mediator release. Structural studies highlight conformational flexibility in IgE and reveal allosteric and orthosteric mechanisms for therapeutic inhibition.

Other names

IgE-FcεRIIgE–Fc epsilon receptor I complexhigh-affinity IgE receptor complexFcεRI–IgE complex

Neutralization of IgE to prevent FcεRI sensitization Dissociation or inhibition of preformed IgE–FcεRI complexes Allosteric inhibition of IgE–FcεRI binding Reduction of cell activation by preventing allergen-induced crosslinking