[The clinical informativeness of detection of antibodies to citrullinated proteins under rheumatoid arthritis].

The main diagnostic laboratory markers of rheumatoid arthritis are IgM rheumatoid factor and antibodies to citrullinated proteins. The IgM rheumatoid factor is a sensitive but insufficiently specific marker of rheumatoid arthritis. The antibodies to citrullinated proteins have a higher specificity for diagnostic of rheumatoid arthritis. The antibodies to cyclic citrullinated peptide and modified citrullinated vimentin are the main representatives of family of antibodies to citrullinated proteins applying in clinical diagnostic practice. The study was carried out to deternine the role of antibodies to citrullinated proteins and modified citrullinated vimentin in diagnostic, evaluation of activity and severity of destructive alterations under rheumatoid arthritis. The samplings of 993 patients with reliable diagnosis of rheumatoid arthritis. 179 patients with other rheumatoid diseases and 30 healthy donors were examined. The measurement of serum concentration of IgM rheumatoid factor and C-reactive protein was implemented by immune nephelometric analysis and antibodies to citrullinated proteins were analyzed by enzymoimmunoassay The erythrocyte sedimentation rate was established using the Westergreen technique. It was established that antibodies to modified citrullinated vimentin had the highest diagnostic specificity (83%), antibodies to cyclic citrullinated peptide had the highest diagnostic specificity (87%). The diagnostic specificity of joint detection of IgM rheumatoid factor, antibodies to citrullinated proteins and antibodies to modified citrullinated vimentin made up to 87%. In patients negative to rheumatoid factor the rate ofdetection of antibodies to citrullinated proteins made up to 34% and antibodies to modified citrullinated vimentin made up to 48%. The diagnostic effectiveness of detection of antibodies to citrullinitted proteins (ratio of likelihood of positive and negative results of test was correspondingly 5.5 and 0.3; area under ROC curve 0.8) and antibodies to modified citrullinated vimentin (ratio of likelihood of positive and negative results of test was correspondingly 4.4 and 0.2; area under ROC curve 0.9) surpassed the same in analysis of IgM rheumatoid factor (ratio of likelihood of positive results--3.2, ratio of likelihood of negative results--0.4, area under ROC curve--0.8). The weak positive correlation relationship was established between concentration of antibodies to cyclic citrillinatedpeptide/antibodies to modified citrullinated vimentin in blood serum and indicators of clinical laboratory activity of rheumatoid arthritis (ESR, CRP DAS 28, (r-0.2. p < 0.05). The high positive levels of antibodies to modified citrullinated vimentin associated with expressed destructive affection of joints (p < 0.02). The antibodies to cyclic citrullinated peptide are the most highly specific and clinically informative laboratory diagnostic marker of rheumatoid arthritis. The detection of antibodies to modified citrullinated vimentin is an important additional serological test to diagnose rheumatoid arthritis in IgM rheumatoid factor-negative and/or antibodies to cyclic citrullinated peptide-negative patients and to forecast severe destructive affection of joints under the given disease. The joint study of IgM rheumatoid factor, antibodies to cyclic citrullinated peptide and antibodies to modified citrullinated vimentin under rheumatoid arthritis has higher diagnostic sensitivity as compared with isolated antibodies to citrullinated proteins.