Anti-nucleosome antibodies in systemic lupus erythematosus

Objective Antinucleosome antibody (AnuA) has recently been described in patients with systemic lupus erythematosus (SLE) and it has been suggested that its presence is associated with lupus nephritis (LN). Methods The groups included 120 consecutive patients with SLE (four or more ACR criteria), 30 healthy blood donors and 55 patients with 7 other connective tissue disease (CTD). Disease activity was assessed using systemic lupus erythematosus disease activity index (SLEDAI). The groups were evaluated for AnuA by enzyme-linked immunosorbent assay (ELISA) and for clinical, humoral parameters and other autoantibodies. Results The prevalence of AnuA in SLE patients and controls was 55.8% and 4.7% respectively, 35% and 1.2% for anti-dsDNA, and 24.2% and 0 for anti-Sm antibody. AnuA had a sensitivity of 55.8% and specificity of 95.3% for SLE diagnosis. AnuA showed the highest correlation with disease activity, especially in patients negative for anti-dsDNA antibodies. The level of AnuA strongly correlated with SLEDAI (t=2.171, P0.05), but inversely correlated with serum complement (C3, C4) levels. AnuA also showed strong association with renal and liver damage. Conclusion The measurement of AnuA appears to be a useful addition to the laboratory tests that can help the diagnosis and treatment of SLE, especially in patients who are negative for anti-dsDNA antibody. The data suggest that the AnuA may be a sensitive and specific for SLE, but isn′t a marker for an increased risk of lupus nephritis. Simultaneous detection of AnuA, anti-dsDNA antibody, anti-Sm antibody and antibody to nuclear antigens (ANA) can notably improve the sensitivity and specificity of SLE diagnosis.