The high affinity receptor for immunoglobulin E:: lessons from structural analysis

The high affinity receptor for Igepsilon, FcepsilonRI, is at the core of the allergic reaction. This receptor is expressed mainly on mast cells and basophils. Interaction of an allergen with its specific IgE bound to FcepsilonRI triggers cell activation, which induces the release of numerous mediators that are responsible for allergic manifestations. The recent increase in the prevalence of allergic diseases in developed countries has resulted in renewed efforts towards the development of new drugs. One of these is a humanised antibody directed against the IgE ligand. This antibody recognises specifically free but not FcepsilonRI-bound IgE thus preventing ligand binding and subsequent cell activation. This antibody has shown some efficacy in clinical trials involving patients with asthma and allergic rhinitis, The recent elucidation of the tridimensional structure of the complex between IgE and FcepsilonRI provides unexpected information regarding the mechanism of assembly of the complex, which now can be used to design small chemical compounds capable of specifically inhibiting this interaction.