Presence of immunoreactive endothelin in synovial fluid: analysis of 22 cases.

Abstract

The endothelins are a family of recently defined active peptides with a wide range of activities, including the activation of the synthesis of prostaglandins. The concentration of endothelin in inflammatory and noninflammatory synovial fluids (SF) was measured by a sensitive radioimmunoassay. Endothelin-like immunoreactivity was detectable in all SF samples and the mean concentration of endothelin was 2.6 +/- 0.3 pg/ml, more than twice that in normal human plasma. The mean level of endothelin in SF in rheumatoid arthritis was 2.5 +/- 0.4 pg/ml (n = 11), and was not statistically different from either osteoarthritis, 3.0 +/- 0.5 pg/ml (n = 7), or acute inflammatory arthritis, 2.0 +/- 0.4 pg/ml (n = 4). Our data do not support the hypothesis that endothelin plays an important role in the pathogenesis of inflammatory arthritis.