Serum and synovial fluid C5a levels in patients with rheumatoid arthritis and Osteoarthritis

Objective: Rheumatoid arthritis (RA) is a chronic, inflammatory disease, with unknown etiology, primarily affects small joints. C5a which is generated during acute flare-up of RA has an important role in the pathogenesis of RA. The aim of this study was to determine C5a levels in plasma and synovial fluid (SF) samples. Material and Methods: Fifteen patients with RA and 13 patients with osteoarthritis (OA) were enrolled in the study. The mean duration of the disease was 6.7 +/- 3.42 years in patients with RA and 8.3 +/- 4.7 years in patients with OA. All patients with RA were active. Synovial fluid was aspirated from the knee joint and at the same time plasma samples were taken from all patients. C5a levels were determined with ELISA. Results:: The mean plasma C5a levels in patients with active RA and OA were 107.3 +/- 18.2 mu gr/L and 88.5 +/- 23.1 mu gr/L respectively. The mean SF C5a level was 168.4 +/- 41.7 mu gr/L in patients with active RA and 103.8 +/- 33.1 mu gr/L in patients with OA. There was no statistically significant difference in plasma C5a levels in both of the groups. The SF C5a levels were significantly high in patients with active RA compared to patients with OA. Conclusion: The high levels of C5a levels in SF of the patients with active RA, suggests that C5a is intensively synthesized in the region of inflammation.