[Anticitrullin antibodies--modern markers of rheumatoid arthritis]

Modern diagnosis of rheumatoid arthritis (RA) is based on the ARA criteria with seropositivity detection by the rheumatoid factor (RF). In a clinically evident stage of the disease this factor is highly sensitive and specific (about 90%), but in early RA efficacy of this diagnosis is considerably less. RF-IgM phenotype has limitation: frequent detection of this factor in the absence of RA and unstability of RF-IgM phenotype. Therefore, it is necessary to search for new serological criteria of RA diagnosis at early stage of the disease. Proteins containing citrullin appear only in the course of posttranslation modification of arginin residues. This fact gave rise to an original, available for clinical practice method of enzyme immunoassay for detection of antibodies to cyclic citrullinized (ACCP)--filaggrin derivative with synthetic cyclic citrullinized peptide serves as antigenic substance. According to the results of different studies, ACCP specificity in early RA diagnosis is more than 80%, combination of ACCP with ESR, RF-IgM, CRP, morning stiffness--more than 90%. As specificity of combination of these autoantibodies is almost 100%, their simultaneous determination is indicated in patients with undifferentiated arthritis for specification of the diagnosis. ACCP and antibodies to modified citrullinized vimentin (AMCV) significantly correlate with RA activity, are prognostic factors of rapidly progressive course and can be used for the disease prognosis at its early stage. Present-day data on comparative specificity and sensitivity of ACCP and AMCV are not certain and need further study.