To investigate the prevalence and levels of anti-cyclic citrullinated peptide antibodies (anti-CCP) in patients with familial Mediterranean fever (FMF) with and without arthritis.
Eighty-three patients with FMF and 43 healthy controls were included in the study. Thirty seven FMF patients had a history of arthritis, and 46 patients did not. Serum antibodies directed to the anti-CCP were assessed with a commercial enzyme-linked immunosorbent assay (ELISA) kit. Values <20U were considered negative, between 20 and 39U low, 40-99U moderate, and >100U high positive.
Positivity rate of anti-CCP in the whole FMF group (14.5%) was three-fold higher than the control group (4.7%). However, the difference failed to achieve a statistically significant level (p=0.09). Anti-CCP levels were 21±30.1 in patients with arthritis and 13.1±10.3 in the non arthritic group (p<0.05). Anti-CCP positivity rates were 10/37 (27%) in patients with arthritis and 2/46 (4.3%) in patients without arthritis (p<0.005). Five FMF patients with arthritis (13.5%) had moderate-high anti-CCP levels (>40U/ml). Anti-CCP levels were between 20-39U/ ml in 2FMF patients without arthritis and in 2 healthy controls. Anti-CCP positivity rate is higher in FMF patients with arthritis (27%) than healthy controls (4.7%) (p<0.005).
Anti-CCP prevalence is higher in FMF patients with arthritis than without arthritis, and that a significant proportion of FMF patients with arthritis (13.5%) had moderate-high titers of anti-CCP. Therefore, anti-CCP antibodies may not be a reliable indicator to differentiate between FMF arthritis and rheumatoid arthritis.