INCREASED LEVELS OF SERUM IGM ANTIBODY TO STAPHYLOCOCCAL-ENTEROTOXIN-B IN PATIENTS WITH RHEUMATOID-ARTHRITIS

Objective-To investigate the role of superantigen in rheumatoid arthri tis (RA) by assaying the serum levels of staphylococcal enterotoxin B (SEB) antibodies. Methods-Serum IgG and IgM SEB antibodies were measur ed using an enzyme linked immunosorbent assay (ELISA), and confirmed b y Western blot analysis. The T cell receptor V beta (TCR V beta) reper toire was analysed using the reverse transcriptase polymerase chain re action. Results-RA patients had increased levels of serum IgM SEB anti body compared with normal subjects, patients with systemic lupus eryth ematosus, Sjogren's syndrome, and Behcet's disease. The titres of rheu matoid factor (RF) showed no correlation with the levels of IgM SEB an tibodies, and the levels of SEB antibodies were not inhibited by the a ddition of human immunoglobulin, or after absorption of RF. RA patient s whose disease duration was less than 10 years had greater levels of serum IgM SEB antibodies than those with disease duration more than 10 years. The levels of IgM and IgG SEB antibodies in synovial fluid fro m RA patients were correlated with those in their sera. Western blot a nalysis detected IgM and IgG SEB antibodies as a band of approximately 30 kDa molecular size. The percentage of TCR V beta 2, V beta 5.2, an d V beta 12 in phytohaemagglutinin stimulated peripheral T cells corre lated significantly with the levels of serum IgM SEB antibody in RA pa tients. Conclusion-These results suggest that SEB, one of the superant igens, may have a critical role in the pathogenesis of RA.