Anti-human IgE monoclonal antibodies recognizing epitopes related to the binding sites of high and low affinity IgE receptors.
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 enzyme-linked immunosorbent assay, Western blotting and a multi-pin peptide technology. Four sites (one each in the C epsilon 1, C epsilon 2, C epsilon 2/C epsilon 3 junction and C epsilon 3) were recognized by the mAbs. The relationship between the four epitopes and the binding sites of high and low affinity IgE receptors (Fc epsilon RI and Fc epsilon RII, respectively) was studied using a monovalent Fab fragment of each mAb as a binding inhibitor. The IgE-Fc epsilon RII binding was clearly inhibited by the mAb recognizing the C epsilon 2/C epsilon 3 junction, suggesting that Fc epsilon RII binds to a rather limited area around the C epsilon 2/C epsilon 3 junction. The IgE-Fc epsilon RI binding, on the other hand, was scarcely inhibited by any single mAb. However, the binding was inhibited when the epitope in C epsilon 2 was blocked simultaneously with that at the C epsilon 2/C epsilon 3 junction or with that in C epsilon 3, indicating that these three distinct epitopes are related to the Fc epsilon RI binding sites. When these three epitopes were shown in the stereograph of human IgE, the Fc epsilon RI binding area was spread largely on the groove side between C epsilon 2 and C epsilon 3 domains. These results suggest that Fc epsilon RI acquires the high affinity through multiple bindings.
Takemoto
H
H
Shionogi Research Laboratories, Medical Science, Shionogi and Co., Ltd., Osaka, Japan.
Nishimura
S
S
Kosada
Y
Y
Hata
S
S
Takagi
S
S
Hosoi
S
S
Ezumi
K
K
Ide
M
M
Harada
S
S
D000595:Amino Acid Sequence; D000818:Animals; D000888:Antibodies, Anti-Idiotypic / Q000276:immunology*; D000911:Antibodies, Monoclonal / Q000276:immunology*; D000918:Antibody Specificity; D001665:Binding Sites; D001666:Binding Sites, Antibody; D001667:Binding, Competitive; D015153:Blotting, Western; D002454:Cell Differentiation; D004797:Enzyme-Linked Immunosorbent Assay; D000939:Epitopes / Q000276:immunology*; D006801:Humans; D007073:Immunoglobulin E / Q000737:chemistry / Q000276:immunology*; D007140:Immunoglobulin Fab Fragments / Q000276:immunology / Q000494:pharmacology; D015464:Leukemia, Myelogenous, Chronic, BCR-ABL Positive / Q000473:pathology; D051379:Mice; D008807:Mice, Inbred BALB C; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009194:Myeloma Proteins / Q000276:immunology; D010446:Peptide Fragments / Q000138:chemical synthesis / Q000276:immunology; D011487:Protein Conformation; D017455:Receptors, IgE / Q000145:classification / Q000276:immunology*; D013045:Species Specificity; D014407:Tumor Cells, Cultured
D000888:Antibodies, Anti-Idiotypic; D000911:Antibodies, Monoclonal; D000939:Epitopes; D007140:Immunoglobulin Fab Fragments; D009194:Myeloma Proteins; D010446:Peptide Fragments; D017455:Receptors, IgE; C026408:anti-IgE antibodies; D007073:Immunoglobulin E