Inactivation of antithrombin III in synovial fluid from patients with rheumatoid arthritis
- aDepartment of Rheumatology, Royal Hampshire County Hospital, Winchester, bInflammation Research Group, St Bartholomew’s and the Royal London School of Medicine and Dentistry, London, cDepartment of Rheumatology, Christchurch Hospital, Christchurch
- Dr H W Jones, Clinical Rheumatology Unit, Guy’s Hospital, London SE1 9RT.
- Accepted 21 January 1998
Abstract
OBJECTIVE To investigate the thrombin inhibitory capacity of antithrombin III in the inflamed human joint.
METHODS Thrombin inhibitory capacity was measured, using a kinetic spectophotometric method, in matched plasma and synovial fluid samples of patients with rheumatoid arthritis (n=22) and osteoarthritis (n=16), together with normal control plasma samples (n=13). In the same samples, the concentration of antithrombin III was also determined by the method of radial immunodiffusion. The combination of these measurements allowed the calculation of the specific thrombin inhibitory capacity of these samples.
RESULTS An increased concentration of antithrombin III in rheumatoid compared with osteoarthritic synovial fluid was noted (p<0.05). However, there was a significant depression in the specific activity of antithrombin III in rheumatoid synovial fluid when compared with matched plasma samples (p<0.001) or with osteoarthritic synovial fluid (p<0.05).
CONCLUSION In rheumatoid synovial fluid the thrombin inhibitory capacity of antithrombin III is disproportionately depressed relative to the concentration of antithrombin III, indicating the inactivation of antithrombin III in the rheumatoid joint.
