AUTOANTIBODIES TO CIRTULLINATED ANTIGENS FOR DIAGNOSIS AND PREDICTION OF CLINICAL COURSE IN EARLY RHEUMATOID ARTHRITIS

Abstract

Abstract. To study the value of antibodies to cirtullinated antigens in diagnosis and their significance in prediction of erosion formation of rheumatoid arthritis (RA), we examined serological status in 129 patients with early RA (ERA) and 55 cases of undifferentiated arthritis, lasting less than 12 months. Another group consisted of 39 patients with long-standing rheumatoid arthritis, in whom the disease persisted for > 2 years. Control group included 39 patients with osteoarthrosis and 29 patients with reactive arthritis. The titers of rheumatoid factor (RF), antikeratin antibodies (AKA), antiperinuclear factor (APF) and antibodies to cyclic citrullinated peptide (anti-CCP) were studied during initial examination and 12 months later. Serial cryosections of rat esophagus and normal human buccal epithelial cells served as substrates for AKA and APF detection. AntiCCPs were revealed by means of DIASTAT technique (Axis Shield, UK).Upon initial observation of the patients with ERA, sensitivity and specificity of anti-CCP was, resp., 63.5% and 97,8%, thus exceeding both parameters for RF (48,8% и 86,7%). Sensitivity of AKA and APF for the same group was 17% and 24 %, with specificity of 97.7%. In RF-seronegative cases of early RA, anti-CCP were detected in 37% with ERA and 42% long-standing RA. In patients with non-differentiated arthritis who developed RA within one year, RF and anti-CCP were found in 12,2% and 45,5%. Following a one-year observation, a statistically significant increase was found in incidence of RF and anti-CCP in ERA patients.Positivity for anti-citrulline antibodies (AKA, APF and anti-CCP) in ERA patients were associated with higher levels of CRP, increased HAQ, DAS4, Sharp scores, as compared to the patients who were seronegative. In ERA patients positive for anti-citrulline antibodies, higher frequencies of synovitis and erosive arthritis were detected by means of ultrasound and magnetic resonance imaging. In the patients with ERA, both RF- and anti-CCP seropositivity represent sufficient risk factors for erosive arthritis within a year after clinical manifestations.

Keywords

• rheumatoid arthritis
• early rheumatoid arthritis
• autoantibodies
• rheumatoid factor
• antikeratin antibodies
• antiperinuclear factor
• cyclic citrullinated peptide