Prevalence of selected organ-specific autoantibodies in rheumatoid arthritis and primary Sjögren's syndrome patients

OBJECTIVES The aim of the study was to investigate the prevalence of selected organ-specific autoantibodies in rheumatoid arthritis (RA) and primary Sjögren's syndrome (pSS) patients, and discuss their clinical significance. MATERIAL AND METHODS The study included 121 RA and 30 pSS patients. Sera were tested for the presence of autoantibodies to thyroid peroxidase (anti-TPO), thyroglobulin (anti-TG), TSH receptor (TRAbs), mitochondrial antigen M2 (AMA-M2-3E) and gliadin-analogous fusion peptides (anti-GAF(3X)) using the ELISA method. Non-organ-specific antibodies were determined: rheumatoid factor in IgM class, anti-citrullinated peptide antibodies and antinuclear antibodies. The occurrence of antibodies was also examined with regards to RA activity. RESULTS The following autoantibodies were detected in RA patients: anti-TPO - 13 (10.7%), anti-TG - 6 (5%), AMA-M2-3E - 3 (2.5%), anti-GAF(3X) - 5 (4.1%). The respective levels of these autoantibodies in pSS patients were 3 (10%), 2 (6.7%), 4 (13.3%) and 2 (6.7%). Polyautoimmunity was confirmed in 34 RA patients (including 20 cases of autoimmune thyroid disease [AITD]) and in 6 pSS patients (6 cases of AITD). When RA patients were divided into anti-TPO positive and anti-TPO negative groups, we found a statistically significant relationship between groups regarding age and hemoglobin concentration. In pSS patients the anti-TPO positive group was less likely to use immunosuppressive drugs as compared with the anti-TPO negative group. Anti-TPO was significantly more frequently detected in RA + AITD vs. RA, RA + SS + AITD vs. RA and in pSS + AITD vs. pSS patients. CONCLUSIONS Organ-specific autoantibodies are relatively frequently observed in patients with RA and pSS. Their presence is connected with the clinical picture of the diseases.