Introduction: Due to the high specificity and strong association with erosive course of the disease, anti-CCP antibodies have recently been suggested as a new diagnostic criterion for rheumatoid arthritis. Positivity of these antibodies before the first clinical manifestation of RA supports the idea of the role of anti-CCP in the pathogenesis of the disease. Aim: to evaluate specificity of anti-CCP antibodies in synovial fluid from patients with rheumatoid arthritis in comparison with activeoste oarthritis of the knee. To evaluate putative correlation between synovial fluid and serum anti-CCP antibodies, activity and functional status of the disease. Patients and methods: Anti-CCP antibodies were measured in serum and synovial fluid from 46 patients with rheumatoid arthritis and 41 patients with osteoarthritis of the knee using commercially available ELISA kit. Results: Good correlation (ρ=0.87, p<0.01) of the mean level of anti-CCP antibodies in serum and synovial fluid was found in patients with rheumatoid arthritis. No significant correlation between the level of anti-CCP, duration of the disease, functional status and activity of rheumatoid arthritis was found. Frequency of positive anti-CCP antibodies was significantly higher in patients with rheumatoid arthritis in contrast to patients with osteoarthritis of the knee (34.8 % vs. 0%, p<0.001). Conclusions: We found a high specificity of positive anti-CCP antibodies in serum and synovial fluid from patients with rheumatoid arthritis in contrast to patients with osteoarthritis. Serum levels of anti-CCP antibodies correlated with synovial fluid levels. Although the role of citrullinated peptides in the pathogenesis of rheumatoid arthritis is not known so far, the presence of antibodies against those proteins seems to be promising diagnostic tool. Moreover, current results of other authors support the idea of potential value for evaluation of anti-CCP antibodies as prognostic marker.

        Key words: rheumatoid arthritis, osteoarthritis of the knee, anti-CCP antibodies, synovial fluid