OBJECTIVE: to determine the frequency of antinucleosome (AN) antibodies in systemic lupus erythematosus (SLE) and their association with disease activity. METHODS: cross-sectional study to evaluate patients with diagnosis of SLE based on the American College of Rheumatology criteria. SLEDAI score was used as a disease activity index. AN antibodies were tested by ELISA (INOVA Diagnostics Inc). Systemic sclerosis (SSc) and myositis patients were also studied to determine the diagnostic performance of the ELISA system. RESULTS: a total of 82 SLE patients, 81 female, mean age 35 ± 11.7 years were included in the study. AN antibodies were positive in 48 SLE samples (58.5%), three with myositis (21.4%) and two with SSc (14.2%), determining a sensitivity and specificity of AN antibodies for the diagnosis of SLE of 58.5% and 82.14%, respectively. Utilizing a cut off of 40 U, test was positive in 45 SLE samples (53.65%), two with myositis (13.33%) and one with SSc (6.66%), determining a sensitivity and specificity of AN antibodies for the diagnosis of SLE of 53.65% and 90%, respectively. There were no correlation between AN antibodies and SLEDAI scores. On the other hand, it was observed a positive correlation between anti-DNA antibodies and disease activity (r = 0.42; p < 0.005). CONCLUSIONS: in the present study it was demonstrated a high specificity and moderate sensitivity of AN antibodies for the diagnosis of SLE. However, the lack of association with disease activity suggests that it has limited value in rheumatologic practice.
systemic lupus erythematosus; antinucleosome; SLEDAI
