High affinity immunoglobulin epsilon receptor (FcεRI) (FcεRI)

The High affinity immunoglobulin epsilon receptor (FcεRI) is the primary molecular initiator of IgE-mediated immediate hypersensitivity reactions. Located predominantly on mast cells and basophils, this multimeric receptor complex binds the Fc region of IgE antibodies with high affinity (UniProt: P12319). When multivalent allergens cross-link the IgE-FcεRI complexes, it triggers a complex intracellular signaling cascade involving Spleen Tyrosine Kinase (Syk) and Phospholipase C gamma (PLCγ). This signaling leads to the depletion of endoplasmic reticulum calcium stores and the subsequent opening of ORAI1 calcium channels, a process known as store-operated calcium entry (SOCE) (PubMed: 25614322). The resulting influx of calcium is the definitive signal for mast cell degranulation, releasing histamine and other pro-inflammatory mediators that cause allergic symptoms. Therapeutic interventions like Omalizumab target this pathway by binding to circulating IgE, thereby preventing its interaction with FcεRI and reducing the density of the receptor on the cell surface (StatPearls: Type I Hypersensitivity). Other approaches include small molecule inhibitors of Syk or mast cell stabilizers that modulate calcium-dependent release mechanisms.

Other names

Fc epsilon RIHigh affinity IgE receptorFCER1IgE receptor type IIgE-mediated immediate hypersensitivity and mast cell Ca2+ influx pathway

Inhibition of IgE binding to the high-affinity receptor, inhibition of downstream Spleen Tyrosine Kinase (Syk) signaling, and stabilization of mast cell membranes to prevent mediator release.