von Willebrand factor in synovial fluid

Von Willebrand factor (vWf), an endothelial product that arises in plasma in conditions associated with vascular damage and acute phase reaction, was evaluated in paired samples of plasma and synovial fluid obtained from 54 patients with inflammatory joint effusion, 19 patients with osteoarthritis, and from the plasma of 19 controls. Synovial fluid levels of vWf were detected in 36 of the patients. The mean value of vWf in the inflammatory joint effusion group was 18.27 +/- 3.03%, significantly higher than the mean value of 7.7 +/- 4.4% found in the osteoarthritis group (p less than 0.01). The significant difference between these groups was maintained when vWf was expressed as a ratio of albumin. vWf was correlated with synovial fluid levels of alpha-1-antitrypsin (r = 0.83, p less than 0.01) and with the white cell count (r = 0.74, p less than 0.01), but not with the levels of immunoglobulins or C3. vWf in the synovial fluid may reflect the local degree of inflammation.