[Plasma and synovial fibronectin. Results of personal research]

The authors report the results of an assay of plasma fibronectin and synovial fluid fibronectin conducted in 104 patients with arthropathy, including 26 cases of rheumatoid arthritis, 43 cases of mechanical arthropathy and 35 cases of non-rheumatoid arthritis. The plasma fibronectin levels do not vary significantly between the different groups of patients, but the mean value for the whole group of patients is significantly lower than that of a control population. The mean value of synovial fluid fibronectin was significantly higher in the patients with rheumatoid arthritis (583 +/- 76 mg/1) than in the patients with non-rheumatoid arthritis (379 +/- 58 mg/1) or mechanical arthropathy (367 +/- 32 mg/1). The assay of synovial fibronectin could therefore provide useful information for the aetiological diagnosis of inflammatory arthropathies. The local origin, from the synovial membrane itself, of the fibronectin in the synovial fluid is suggested by the fact that the synovial concentration of this protein is superior to the serum concentration in 50 to 90 per cent of cases, depending on the disease.