Correlation of metal-binding proteins and proteinase inhibitors with immunological parameters in rheumatoid synovial...

Metal-binding proteins (ceruloplasmin, transferrin, ferritin, and lactoferrin), proteinase inhibitors (alpha 1-antitrypsin, alpha 2-macroglobulin and inter-alpha-trypsin inhibitors), and albumin were assayed in synovial fluid obtained from 20 patients with rheumatoid arthritis (RA) and 15 with osteoarthritis (OA). The levels of proteinase inhibitors and metal-binding proteins, except transferrin, were significantly increased in synovial fluid from RA patients as compared with synovial fluid from OA patients. Metal-binding proteins significantly correlated with rheumatoid factor and immune complexes in synovial fluid from RA patients. Proteinase inhibitor levels also significantly correlated with C-reactive protein, and complement components. These results suggest that the raised level of metal-binding proteins and proteinase inhibitors in synovial fluid from RA patients reflect inflammatory activity, and hence may play an important role in the pathogenesis of inflammatory joint diseases.