Autoantigenicity of DFS70 is restricted to the conformational epitope of C-terminal alpha-helical domain

• Published in: Journal of autoimmunity Vol. 23; no. 3; pp. 221 - 231
• Main Authors: Ogawa, Yasushi, Sugiura, Kazumitsu, Watanabe, Akihiro, Kunimatsu, Mitoshi, Mishima, Masaki, Tomita, Yasushi, Muro, Yoshinao
• Format: Journal Article
• Language: English
• Published: London Elsevier Ltd 01.11.2004; Elsevier
• Subjects: Adaptor Proteins, Signal Transducing; Adolescent; Adult; Aged; Amino Acid Sequence; Animals; Autoantigens - chemistry; Autoantigens - genetics; Autoantigens - immunology; Autoimmunity; Biological and medical sciences; Child; Circular Dichroism; Conformation; DFS70/LEDGF; Epitope; Epitope Mapping; Epitopes - chemistry; Epitopes - genetics; Epitopes - immunology; Female; Fundamental and applied biological sciences. Psychology; Fundamental immunology; General aspects; Humans; Immune Sera - immunology; Immunopathology; Immunoprecipitation; Male; Medical sciences; Middle Aged; Molecular Sequence Data; Mutation - genetics; Natural autoantibody; Protein Structure, Secondary; Protein Structure, Tertiary; Sequence Alignment; Tissue Donors; Trans-Activators - chemistry; Trans-Activators - genetics; Trans-Activators - immunology; Transcription Factors; Autoimmunity; Epitope; DFS70/LEDGF; Conformation; Natural autoantibody; C terminal-Sequence; Immunopathology; Autoantigen; Immunology; Antigenic determinant; Antibody; Autoantibody
• ISSN: 0896-8411; 1095-9157
• DOI: 10.1016/j.jaut.2004.07.003

Autoantibodies against DFS70 (Dense Fine Speckles 70) are found in 30% of Japanese atopic dermatitis patients, and less frequently in patients with other diseases. We have recently reported that they are also seen in 11% of hospital workers, but in only ∼2% of patients with systemic rheumatic disease. In this study, in order to investigate the possible pathological role of anti-DFS70 antibodies, fine epitope mapping was carried out using 93 anti-DFS70 autoantibody-positive sera. Immunoblotting using overlapping peptides failed to reveal major linear epitopes. Western blotting using various truncated proteins showed a strikingly uniform epitope distribution on a suspected tertiary structure expressed by DFS70 349–435. Some sera showed reactivity only in an immunoprecipitation assay using an in vitro translated DFS70. Circular dichroism analysis revealed that DFS 349–435 contains an approximately 40% alpha-helical conformation, while an overlapping, non-antigenic peptide is composed of random coiled structures. The skewed single major epitope enabled us to establish a highly quantitative ELISA for the epitope region. Antibody titers showed no significant differences between the diseased group and healthy individuals. We propose that anti-DFS70 antibody may be a natural autoantibody, which might modify or reflect the inflammatory process of various disorders.