Anti-cyclic citrullinated peptide antibodies in rheumatoid arthritis, brucellar arthritis and Behcet's disease

In Behcet's disease (BD) and Brucellosis, joint involvement is very common and it may share similarities with rheumatoid arthritis (RA). Anti-cyclic citrullinated peptides (CCP) are evaluated as more specific autoantibodies than rheumatoid factor (RF) in RA. The aim of this study is to determine whether anti-CCP antibodies are useful in the differential diagnosis of RA from other arthritis or not. 153 serum samples were used in the study; 34 from RA patients, 26 from brucellar arthritis, 20 from BD with arthritis, 41 from BD without arthritis and 32 from healthy controls. In vitro quantitative, anti-CCP levels were measured by using fluoroenzyme-immunoassay (FEIA) method. Among RA patients, 73.5% were anti-CCP-positive and 70.5% were RF-positive. While there was a statistical difference in the anti-CCP and RF positivity rates between RA and brucellar arthritis patients, BD patients and healthy controls (p = 0.0001), there was no statistical difference between BD patients with arthritis and BD patients without arthritis. Also none of the Brucellar arthritis patients was positive for anti-CCP antibodies, one of them were positive for RF. Our results indicate that anti-CCP antibodies are not associated with brucellar arthritis or BD with joint involvement and since they show high specificity and good sensitivity for RA, they can be evaluated as a better marker than RF especially for the differentiation of RA from other types of arthritis such as BD and brucellar arthritis.