再訪Anti-CCP抗體

Anti-CCP antibody, revisited

Since joint destruction occurs soon after the onset of rheumatoid arthritis (RA), the current treatment strategy is shifting towards aggressive antirheumatic therapy in the early stage of the disease. However, the early diagnosis of RA based solely on the 1987 revised criteria of the American College of Rheumatology can be inaccurate, especially when the clinical presentation is atypical and rheumatoid factor (RF), the only serological marker used in the criteria, is negative. Over the last several years, several autoantibodies reactive to citrullinated proteins, including anti-perinuclear factor (APF), antikeratin antibody (AKA), anti-filaggrin, and antivimentin (anti-Sa) antibodies, have attracted interest due to their association with RA. The most noteworthy of these is anti-cyclic citrullinated peptide (anti-CCP) antibody, directed to the modified cyclic citrullinated peptide located in the major epitope of filaggrin molecules. For the diagnosis of RA, compared to IgM-RF, anti-CCP has been reported to have a comparable sensitivity (41%-87.6% for CCP vs. 54%-86% for IgM-RF) but a superior specificity (88.9%-98.5% vs. 81%-87% for IgM-RF) [1-5]. In very early untreated RA with a disease duration of less than 6 months, the diagnostic sensitivity of anti-CCP was found to be 67.4%, which was lower than that of RF (83.6%); however, the specificity, positive predictive value, and diagnostic accuracy were greater for anti-CCP than RF [6]. In addition, in studies dealing with seronegative early RA or atypical inflammatory arthritis, anti-CCP had a sensitivity of 60%-63.4% and a specificity of 92%-96.1% specificity for making the diagnosis [7,8]. It is now generally agreed that anti-CCP is a useful supplement to RF testing to establish an early diagnosis of RA.