High-affinity immunoglobulin E receptor complex (IgE bound to Fc epsilon RI) (FcεRI–IgE complex)

The high-affinity immunoglobulin E receptor complex ((FcεRI–IgE complex)) is composed of immunoglobulin E (IgE) bound to its primary cell-surface receptor Fc epsilon RI (FcεRI), which is expressed predominantly on mast cells, basophils, and several types of antigen-presenting cells[1][2][3][4][6]. FcεRI is a multi-subunit receptor: in humans, it exists mainly as a tetramer (αβγ2) on mast cells and basophils and as a trimer (αγ2) on other immune cells[1][3][4]. The α subunit binds IgE with exceptionally high affinity (KA ≈ 10¹⁰ M⁻¹)[2][5], while β and γ subunits mediate intracellular signaling following receptor aggregation[1][4]. Cross-linking of FcεRI-bound IgE by multivalent allergens triggers cell activation and degranulation, releasing mediators such as histamine and leukotrienes that drive immediate hypersensitivity reactions, including anaphylaxis[2][3][6]. FcεRI–IgE also plays an important role in antigen uptake and presentation in antigen-presenting cells, contributing to adaptive immunity and occasionally to anti-tumor immunity[2][3]. Therapeutically, the IgE–FcεRI axis is a validated drug target for allergic diseases, with monoclonal antibodies like omalizumab and ligelizumab effectively blocking IgE–FcεRI interaction to prevent mast cell and basophil activation[6].

Other names

High-affinity IgE receptor complexFc epsilon RI–IgE complexFcεRI–IgEIgE receptorFcεRIFc epsilon receptor I

Inhibits binding of IgE to FcεRI (preents receptor activation and cell degranulation); Blocks cross-linking of FcεRI-bound IgE by allergen (preents allergic mediator release); Reduces FcεRI surface expression by lowering free IgE levels; Disrupts IgE–FcεRI interaction