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

The high-affinity immunoglobulin E receptor (FcεRI) bound to immunoglobulin E (IgE) is a central molecular complex in immediate allergic reactions and immunity against parasites. FcεRI is a tetrameric (αβγ₂) or trimeric (αγ₂) cell-surface receptor primarily found on mast cells and basophils, consisting of an α chain (which binds IgE), a β chain (amplifying signaling), and a disulfide-linked γ-chain homodimer (required for signal transduction)[1][3][5][6][8][9]. When an allergen cross-links IgE antibodies attached to FcεRI, this triggers powerful intracellular signaling cascades (involving phosphorylation of ITAMs by Src-family kinases) culminating in degranulation—release of histamine and other mediators—resulting in allergic symptoms ranging from mild local inflammation to life-threatening anaphylaxis[2][5][8][10]. FcεRI–IgE complexes are targeted therapeutically by anti-IgE antibodies (e.g., omalizumab) to reduce the allergic response[4][5][6]. This target is widely considered canonical for drug development in allergy, but the query form ("IgE antibodies bound to FcεRI on mast cells and basophils") is not the standard designation; it combines a ligand and its receptor in cell context rather than referring to a single molecular entity. The correct canonical form is "High-affinity immunoglobulin E receptor (FcεRI)," optionally specifying its IgE-bound state.

Other names

Fc epsilon RI–IgE complexFcεRI–IgEIgE:FcεRIhigh-affinity IgE receptor–IgE complex

Inhibition of IgE–FcεRI binding; Down-regulation of FcεRI surface expression; Blockade of mast cell/basophil activation