It is known that anti-citrullinated protein (a-CCP) antibodies and rheumatoid factor (RF) can be present in systemic sclerosis (SSc) patients, particularly with joint involvement.
The aim of the study was to assess the prevalence of a-CCP antibodies and immunoglobulin M class (IgM) RF, and the relationships between their presence and joint manifestations in patients with SSc.
The study included 100 European Caucasian SSc patients hospitalized consecutively in the Department of Rheumatology and Connective Tissue Diseases (Lublin, Poland). Anti-citrullinated protein antibodies and IgM RF were determined using a commercial enzyme-linked immunosorbent assay (ELISA) test.
Anti-citrullinated protein antibodies were found in 10 out of 100 (10%) SSc patients and IgM RF in 71 out of 100 (71%) SSc patients. In the study, 90/100 (90%) SSc patients had joint manifestations (arthralgia or arthritis), 34/100 (34%) had arthritis and 6/100 (6%) had a systemic sclerosis-rheumatoid arthritis (SSc-RA) overlap syndrome. Significantly higher a-CCP antibody levels (p = 0.012), erythrocyte sedimentation rate (ESR) (p = 0.029) and C-reactive protein (CRP) levels (p = 0.020) were observed in the SSc group with arthritis. A significant correlation was found between the group with arthritis and the presence of a-CCP antibodies, and between the arthralgia group and the presence of IgM RF.
The prevalence of RF and a-CCP antibodies is relatively high in SSc, and joint involvement occurs frequently. There was a significantly higher prevalence of IgM RF in the group with joint manifestations. About 1/3 of SSc patients had symptoms of arthritis. Arthritis is connected with the presence of a-CCP antibodies, while arthralgia is connected with the presence of IgM RF.