Anti-Human IgE Monoclonal Antibodies Recognizing Epitopes Related to the Binding Sites of High and Low Affinity IgE Receptors

• Published in: MICROBIOLOGY and IMMUNOLOGY Vol. 38; no. 1; pp. 63 - 71
• Main Authors: Takemoto, Hiroshi, Nishimura, Shinji, Kosada, Yumi, Hata, Satoshi, Takagi, Shin, Hosoi, Susumu, Ezumi, Kiyoshi, Ide, Misao, Harada, Shigenori
• Format: Journal Article
• Language: English
• Published: Tokyo Blackwell Publishing Ltd 01-01-1994; Center For Academic Publications Japan; Center for Academic Publications Japan
• Subjects: Amino Acid Sequence; Animals; Anti-human IgE monoclonal antibody; Antibodies, Anti-Idiotypic - immunology; Antibodies, immunoglobulins; Antibodies, Monoclonal - immunology; Antibody Specificity; Binding site; Binding Sites; Binding Sites, Antibody; Binding, Competitive; Biological and medical sciences; Blotting, Western; Cell Differentiation; Enzyme-Linked Immunosorbent Assay; Epitopes - immunology; Fundamental and applied biological sciences. Psychology; Fundamental immunology; High and low affinity IgE receptors; Humans; Immunoglobulin E - chemistry; Immunoglobulin E - immunology; Immunoglobulin Fab Fragments - immunology; Immunoglobulin Fab Fragments - pharmacology; Leukemia, Myelogenous, Chronic, BCR-ABL Positive - pathology; Mice; Mice, Inbred BALB C; Models, Molecular; Molecular immunology; Molecular Sequence Data; Monoclonal antibodies; Myeloma Proteins - immunology; Peptide Fragments - chemical synthesis; Peptide Fragments - immunology; Protein Conformation; Receptors, IgE - classification; Receptors, IgE - immunology; Species Specificity; Tumor Cells, Cultured; Human; Specificity; Antigenic determinant; IgE; Binding site; Monoclonal antibody; Recognition; Biological receptor
• ISSN: 0385-5600; 1348-0421
• DOI: 10.1111/j.1348-0421.1994.tb01745.x

Anti-human IgE monoclonal antibodies (mAbs) were produced and eight clones recognizing epitopes on native IgE were selected. Epitopes were mapped by a competitive inhibition enzymelinked immunosorbent assay, Western blotting and a multi-pin peptide technology. Four sites (one each in the Cε1, Cε2, Cε2/Cε3 junction and Cε3) were recognized by the mAbs. The relationship between the four epitopes and the binding sites of high and low affinity IgE receptors (FcεRI and FcεRII, respectively) was studied using a monovalent Fab fragment of each mAb as a binding inhibitor. The IgE-FcεRII binding was clearly inhibited by the mAb recognizing the Cε2/Cε3 junction, suggesting that FcεRII binds to a rather limited area around the Cε2/Cε3 junction. The IgE-FcεRI binding, on the other hand, was scarcely inhibited by any single mAb. However, the binding was inhibited when the epitope in Cε2 was blocked simultaneously with that at the Cε2/Cε3 junction or with that in Cε3, indicating that these three distinct epitopes are related to the FcεRI binding sites. When these three epitopes were shown in the stereograph of human IgE, the FcεRI binding area was spread largely on the groove side between Cε2 and Cε3 domains. These results suggest that FcεRI acquires the high affinity through multiple bindings.