Signalling through the high-affinity IgE receptor FcεRI

The Fc epsilon RI complex forms a high-affinity cell-surface receptor for the Fc region of antigen-specific immunoglobulin E (IgE) molecules. Fc epsilon RI is multimeric and is a member of a family of related antigen/Fc receptors which have conserved structural features and similar roles in initiating intracellular signalling cascades. In humans, Fc epsilon RI controls the activation of mast cells and basophils, and participates in IgE-mediated antigen presentation. Multivalent antigens bind and crosslink IgE molecules held at the cell surface by Fc epsilon RI. Receptor aggregation induces multiple signalling pathways that control diverse effector responses. These include the secretion of allergic mediators and induction of cytokine gene transcription, resulting in secretion of molecules such as interleukin-4, interleukin-6, tumour-necrosis factor-alpha and granulocyte-macrophage colony-stimulating factor. Fc epsilon RI is therefore central to the induction and maintenance of an allergic response and may confer physiological protection in parasitic infections.