[Rinsho Byori 51 : 627〜632, 2003]

Characterization of Anti-DNA Antibody on IgG3-κ type M-protein
in a Patient with Rheumatoid Arthritis

Hirohisa SATO*1, Norio TERASAWA*2, Mitsuomi KAIMORI, MD*3,
Hiromitsu TAKEMORI, MD*4, Teruko OTAKE*5 and Ikunosuke SAKURABAYASHI, MD, PhD*6

A 66 year-old male patient with rheumatoid arthritis, was admitted due to bronchial pneumonia. Anti-nuclear antibody and anti-DNA antibody were both detected in the patient’s serum and many LE-like cells were found in the pleural effusion. In addition, M-proteins(IgG-κ type，IgM-κ type) were detected in both serum and pleural effusion by immunofixation electrophoresis.
Purified IgG fraction by gel filtration(Superdex 200HR) showed high titer of anti-nuclear antibody(×160) and anti-DNA(39.2 AU/ml) antibody. Furthermore, anti-DNA antibody was detected in the fraction III(fraction of M-protein) by ion-exchange chromatography.
In conclusion, these results indicate that M-protein(IgG3-κ type) contains anti-DNA antibody and it is suggests that M-protein induces the production of LE like cell in this case.

*1Department of Clinical Pathology, Aomori Prefectural Central Hospital, Aomori 030-8553