High-affinity immunoglobulin E receptor–immunoglobulin E complex (FcεRI–IgE complex)

The **high-affinity immunoglobulin E receptor–immunoglobulin E complex** (FcεRI–IgE complex) is a multimeric protein assembly found on the surface of mast cells and basophils, playing a central role in allergic reactions[1][2][3][4][7]. FcεRI is a tetrameric complex—composed of one α chain (FcεRIα), one β chain (FcεRIβ), and a homodimer of γ chains (FcRγ)—where the α subunit binds specifically and with very high affinity to the Fc region of IgE[1][2][3][6][8]. IgE molecules, produced by B cells, bind to FcεRIα on mast cells/basophils, sensitizing them to allergens. Upon exposure to a specific allergen, crosslinking of the cell-bound IgE triggers receptor aggregation, leading to signal transduction through ITAM motifs in the β and γ chains. This cascade results in rapid cellular degranulation and release of histamine, prostaglandins, and other inflammatory mediators, causing allergic manifestations up to life-threatening anaphylaxis[3][4][5][6][8]. Drugs such as omalizumab disrupt this pathway by preventing IgE binding to FcεRI, thereby dampening allergic responses. This receptor complex is a validated therapeutic target for allergy and asthma—its structure and function are highly conserved in humans, but differences exist between species with respect to chain composition and regulation[1][2][6][8].

Other names

Fc epsilon RI–IgE complexFcεRI–IgEIgE receptor complexHigh-affinity IgE receptor–IgE complexIgE–FcεRI

Inhibition/blockade of IgE binding to FcεRI Downregulation of FcεRI expression on mast cells and basophils Prevention of mast cell/basophil activation and degranulation