Elucidation of the Epitope Locations of Human Autoanti-IgE: Recognition of Two Epitopes Located within the Cε2 and the Cε4 Domains

Abstract

IgG autoanti-IgE is detectable in a large proportion of individuals with allergic asthma, where it is suggested to be potentially involved in modulating IgE-mediated hypersensitivity. Using a series of overlapping recombinant human ε-chain peptides, we have shown that circulating IgG anti-IgE antibodies recognise at least 2 epitopes located within the Cε2 and the Cε4 domains, respectively. The Cε2 recognition site is located within the C-terminal portion of the Cε2 domain (i.e. aa301–339) which is thought to contribute residues to the FcεRI-binding site on IgE. The recognition by autoanti-IgE of an effector function site of such pivotal importance in IgE-mediated hypersensitivity suggests that it plays a possible modulatory role during mast cell and basophil activation.