Studies on the Myeloproxidase in Synovial Fluid and Elastase in Plasma from Patients with Reumatoid Arthritis

Abstract

The myeloperoxidase activity of synovial fluid and elastase in plasma were examined in patients with rheumatoid arthritis (RA) or osteoarthritis (OA) and control subjects. The elastase activity was significantly higher in RA patients than control subjects (mean ± SD 345.1 ± 187.6pg/1 versus 143.1 ± 67.5μg/l ; p<0.001). The myeloperoxidase activity insynovial fluid was determined by using a guaiacol method with a fixed time rate assay. The myeloperoxidase activity were significantly higher in RA patients than OA patients (mean ±SD 224±134μ/l versus 18±15μ/l;p<0.02). These results indicated that myeloperoxidase is secreted from neutrophils together with elastase. In view of known formation of reactive oxidants by synovial neutrophils, we propose that an extracellular myeloperoxidase-H₂O₂ system plays an important role in tissue damage.