The prevalence of antinuclear antibodies in patients with sarcoidosis

Introduction. Sarcoidosis, which is a chronic inflammatory granulomatous disease, can mimic different rheumatologic diseases including connective tissue diseases. Antinuclear antibodies are the markers used for connective tissue diseases. Aim. To determine antinuclear antibody frequency and any possible correlation with clinical and laboratory data in sarcoidosis patients. Material and Method. Forty-two sarcoidosis patients, 45 rheumatoid arthritis patients, and 45 healthy volunteers who were followed up in rheumatology outpatient clinic were included in this study. Demographic, clinical, serological, and radiological data of all patients were recorded. Antinuclear antibodies were determined with indirect immunofluorescent method and 1/100 titration was accepted as positive. The cases that were ANA positive were evaluated with immunoblot method. Results. Average age of the 42 patients (10 males) with sarcoidosis was 45.2 (20-70 years), and average disease duration was 3.5 years. ANA positivity was detected in 12 (28.5%) patients with sarcoidosis (1/100 in 10 patients, 1/320 in two patients), in 19 of RA patients (42.2%), and in two of healthy volunteers in low titer (P < 0.001). In the subgroup analysis made by immunblot test, one patient had anticentromere antibody, one had anti-Ro antibody, one had anti-Scl-70 antibody, one had anti-dsDNA antibody, and eight patients were negative. The two patients who had anticentromere and anti-Scl-70 antibodies had also Sjögren's syndrome and scleroderma diagnosis, respectively. Discussion. The prevalence of ANA in patients with sarcoidosis was found to be significantly higher than healthy control group and lower than RA patients. This result shows that ANA may have an important role in the pathogenesis of sarcoidosis and also could be important in revealing the overlap syndromes of sarcoidosis-connective tissue diseases. Further studies with larger series are necessary in this subject.