ANTI-SA ANTIBODY IN CHINESE RHEUMATOID-ARTHRITIS

Objective To test anti-Sa antibody in different autoimmune connective tissue diseases and analyze the relationship between Sa antibody and c linical manifestations and laboratory tests in rheumatoid arthritis. M ethod Sa antigen was extracted from human placenta. Anti-Sa antibody w as tested in 40 normal people and 478 connective tissue disease (CTD) patients using Western Blotting (WE). Results Sa antigen was a protein with molecular weights of 50 kD and 55 kD. Anti-Sa antibody was posit ive in 31.9% (61/191) rheumatoid arthritis (RA), 3.0% (2/67) Sjogren's syndrome (SS), 4.3% (2/46) systemic lupus erythmatosus (SLE) and 0% ( 0/66) Behcet's disease, 0% (0/60) polymyositis/dermatomyositis (PM/DM) , 0%(0/66) other CTD and 0% (0/40) normal controls. Anti-Sa antibody w as different from other auto-antibodies in RA. In rheumatoid arthritis its sensitivity, specificity, positive prediction rate, negative pred iction rate were 31.9%, 98.6%, 93.8% and 68.5% respectively. Anti-Sa a ntibody positive patients were significantly different from anti-Sa an tibody negative patients in morning stiffness, ESR, ANA and X-ray grad e. Conclusion Anti-Sa antibody was a new autoantibody for the diagnosi s of RA. Anti-Sa antibody positive patients seem to have more serious inflammation and more advanced disease process.