Rigby LJ, Trist H, Snider J, Hulett MD, Hogarth PM, Rigby LJ, Epa VC. Monoclonal antibodies and synthetic peptides define the active site of FcepsilonRI and a potential receptor antagonist.
Allergy 2000;
55:609-19. [PMID:
10921459 DOI:
10.1034/j.1398-9995.2000.00485.x]
[Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Defining the structure of the human high-affinity receptor for IgE, Fc,RI, is crucial to understand the receptor:ligand interaction, and to develop drugs to prevent IgE-dependent allergic diseases. To this end, a series of four anti-FcepsilonRI monoclonal antibodies (mAbs), including three new mAbs, 47, 54, and 3B4, were used in conjunction with synthetic FcepsilonRI peptides to define functional regions of the Fc IgE-binding site and identify an antagonist of IgE binding. The spatial orientation of the epitopes detected by these antibodies and their relationship to the IgE-binding region of FcepsilonRI was defined by a homology model based on the closely related FcepsilonRIIa. Using recombinant soluble FcRI-alpha as well as FcepsilonRI-alpha expressed on the cell surface, a series of direct and competitive binding experiments indicated that the mAbs detected nonoverlapping epitopes. One antibody (15-1), previously thought to be located close to the IgE-binding site, was precisely mapped to a single loop within the IgE-binding site by both mutagenesis and overlapping synthetic peptides encompassing the entire extracellular domain. A synthetic peptide epsilonRI-11, containing the amino acids 101-120 and the mAb 15-1 epitope, inhibited IgE binding and may form the basis for the development of a useful receptor-based therapy.
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