Background: Heat-shock proteins are part of a strictly controlled biological system that allows organisms to respond to environmental stresses. Different proinflammatory cytokines are present in the synovial tissue of rheumatoid arthritis patients. Such tissues respond to stress and induce heat-shock proteins. In addition, synovial cells are exposed to mechanical stress caused by joint motion. The effects of mechanical stress on the metabolism of the synovial cells may be substantial, even pathogenic. Heat-shock proteins are often implicated in the pathogenesis of rheumatoid arthritis. Here, we compare the levels of heat-shock protein 70 from the synovial fluid of rheumatoid arthritis and osteoarthritis patients.

Methods: Synovial fluid samples from 34 rheumatoid arthritis patients and 34 osteoar-thritis patients were analyzed for heat-shock protein 70 by an ELISA method. Statistical analysis was performed using independent T-test and one-way ANOVA. Differences were considered statistically significant at p< 0.05.

Results: The mean value of synovial fluid heat-shock protein 70 levels in rheumatoid arthritis patients was 156.30 ±128.51 and that of osteoarthritis patients was 14.98 ±11.58. The differences were statistically significant at p<0.0001. For seven rheumatoid arthritis patients suffering from mechanical knee pain, synovial fluid analysis revealed non-inflammatory effusion. The mean value of synovial fluid heat-shock protein 70 level in inflammatory synovial fluid of rheumatoid arthritis patients was significantly higher at 191±121.73 and that of non-inflammatory synovial fluid from rheumatoid arthritis patients was 21.93 ±10.06 (p< 0.05).