Immunoglobulin E receptor (Fc epsilon RI) (FcεRI)

Immunoglobulin E receptor (Fc epsilon RI) is the main high-affinity receptor for immunoglobulin E (IgE) and is expressed on the surface of mast cells, basophils, dendritic cells, and some other immune cells[1][2][3][4][6]. This multimeric transmembrane protein consists of several subunits (α, β, γ chains), with the α-chain directly binding IgE via its Fc region, and the β and γ chains involved in signal transduction[1][2]. Upon cross-linking by allergen-bound IgE, FcεRI triggers intracellular signaling cascades that lead to effector functions such as degranulation, cytokine release, and initiation of allergic and inflammatory responses[1][3][6]. It plays a central role in type I hypersensitivity (allergic) reactions, chronic inflammation, asthma, and also contributes to defense against parasitic infections[5][7]. Therapeutic targeting of the IgE–FcεRI pathway (e.g., with omalizumab) reduces allergic symptoms, but can be associated with immune suppression and risk of severe hypersensitivity[3][5]. Two main IgE-binding receptors exist: the high-affinity FcεRI and the low-affinity CD23 (FcεRII), but FcεRI is most clinically relevant for allergic disease[3][4].

Other names

High-affinity IgE receptorFc epsilon RIFcεRIType I IgE receptorCD23 (for low-affinity receptor, note distinction)

Blocking IgE binding to FcεRI; Competitive inhibition of IgE; Downregulation of receptor expression; Inhibition of mast cell degranulation