Detection of oncostatin M in synovial fluid from patients with rheumatoid arthritis.

OBJECTIVE To measure oncostatin M (OSM) in synovial fluid from patients with rheumatoid arthritis (RA) and osteoarthritis (OA). METHODS 20 samples of synovial fluid from patients with RA and 10 samples from patients with OA were examined using an OSM specific sandwich ELISA. RESULTS OSM was detected at concentrations ranging from 2.36 to 901.82 pg/ml in 18 (90%) of 20 samples of synovial fluid from RA patients. There was no detectable OSM in synovial fluid from OA patients. In the RA patients, the OSM concentration in synovial fluid correlated significantly with the synovial fluid white blood cell count (r = 0.67, p < 0.01), but not with other laboratory parameters of disease activity. CONCLUSION These findings suggest that OSM may contribute to joint inflammation in RA.