High-affinity immunoglobulin E receptor (Fc epsilon RI) complex (FcεRI complex)

The high-affinity immunoglobulin E receptor (FcεRI) is a multimeric transmembrane receptor complex predominantly expressed on the surface of mast cells and basophils, with lower expression on antigen-presenting cells such as dendritic cells and monocytes in humans[1][2][3][4][6]. Its canonical form consists of an IgE-binding α subunit, a signal-amplifying β subunit, and a homodimer of γ subunits responsible for intracellular signal transduction[1][2][3][6]. FcεRI binds immunoglobulin E (IgE) with exceptionally high affinity, enabling sensitization of mast cells and basophils. Upon allergen exposure and cross-linking of IgE/FcεRI complexes, rapid effector cell activation occurs, leading to degranulation and the release of histamine and other pro-inflammatory mediators responsible for acute allergic reactions such as anaphylaxis[3][4][5][8]. This receptor complex is the principal therapeutic target for monoclonal antibodies in allergic diseases, with therapies like omalizumab functioning by blocking IgE-FcεRI interaction and preventing cell activation[5][8]. Targeting the IgE/FcεRI axis remains a key strategy in treating allergic and certain inflammatory conditions, but also presents challenges related to safety and host defense[3][4].

Other names

High-affinity IgE receptor complexFcεRIFc epsilon RIIgE receptorFcεRIαβγ₂ complexImmunoglobulin E receptor

Blockade of IgE binding to FcεRI, preventing mast cell and basophil activation \nDownregulation of FcεRI expression on effector cells \nInhibition of allergic effector functions (e.g., degranulation, mediator release)