Increased serum proMMP-3 in inflammatory arthritides: a potential indicator of synovial inflammatory monokine activity.

OBJECTIVE To investigate if the increased concentrations of stromelysin (MMP-3) found in the synovial fluid (SF) of patients with various arthritides reflect the concentrations in the circulation. METHODS Using a double antibody ELISA, we have measured proMMP-3 concentrations in sera from these patient groups and in others with a heightened acute phase response (APR) as a result of multiple organ failure. RESULTS The median serum concentration of proMMP-3 was increased by up to ninefold in the inflammatory arthritides, but not in osteoarthritis or in patients with a heightened APR resulting from a non-chronic inflammatory condition. CONCLUSION In chronic inflammatory diseases such as rheumatoid arthritis, serum proMMP-3 may prove to be a more specific indicator of monokine activity than currently available serum markers.