Journal Article

Human Anti–Human IL-18 Antibody Recognizing the IL-18–Binding Site 3 with IL-18 Signaling Blocking Activity

Takayuki Hamasaki, Shuhei Hashiguchi, Yuji Ito, Zenichiro Kato, Kenji Nakanishi, Toshihiro Nakashima and Kazuhisa Sugimura

in The Journal of Biochemistry

Published on behalf of The Japanese Biochemical Society

Volume 138, issue 4, pages 433-442
Published in print October 2005 | ISSN: 0021-924X
Published online October 2005 | e-ISSN: 1756-2651 | DOI:
Human Anti–Human IL-18 Antibody Recognizing the IL-18–Binding Site 3 with IL-18 Signaling Blocking Activity

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IL-18 is an important regulator in both innate and acquired immune responses. The aberrant expression of IL-18 is associated with severe inflammatory conditions, such as autoimmune diseases and allergies. Thus, human antibodies with inhibitory activity on IL-18 signaling may be useful for therapeutic applications. We report here the first establishment of an antagonistic anti–IL-18 complete human antibody, h18-108, employing a human single chain antibody (scFv)–displaying phage library. The h18-108 scFv inhibited the IFN-γ production of a human myelomonocytic cell line, KG-1. Flow cytometry analysis showed that h18-108 blocked the binding of IL-18 to KG-1 cells. Epitope mapping analysis using two kinds of random peptide–displaying phage libraries and an IL-18 alanine mutant (D98A) demonstrated that the h18-108 scFv binds to the site 3 of IL-18, which is suggested to be an association site with the IL-18 receptor β. The complete human Fab and IgG forms of h18-108 have been successfully constructed to attain increases in both binding affinity and inhibitory activity.

Keywords: allergy; epitope mapping; interleukin-18; human antibody; phage display; AP, alkaline-phosphatase; CDR, complementarity determining region; FR, framework; HPLC, high performance liquid chromatography; HRP, horseradish peroxidase; IC50, 50% inhibitory concentration; IGIF, IFN-gamma inducing factor; IgG, immunoglobulin G; IgM, immunoglobulin M; IL-18, interleukin-18; IL-18Rα, interleukin-18 receptor α; IL-18Rβ, interleukin-18 receptor β; IL-1RAcPL, interleukin-1 receptor accessory protein–like; IL-1Rrp, interleukin-1 receptor related protein; LPS, lipopolysaccharide; mAb, monoclonal Ab; RU, response unit; scFv, single-chain variable fragment; TU, transformation unit

Journal Article.  5831 words.  Illustrated.

Subjects: Biochemistry

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