The diagnostic value of antihistone antibodies in drug-induced lupus erythematosus.

This study was undertaken to see whether the presence of antihistone antibodies, measured by indirect immunofluorescence assay, could distinguish between patients who were symptomatic from a drug-induced lupus-like illness (DILE) and asymptomatic patients who had drug-induced antinuclear antibodies (DANA). In this study, 82% of the patients with DILE had antihistone antibodies detectable in their sera, compared with 32% of the patients in the DANA group (P less than 0.01). When the patients taking procainamide were analyzed separately, it was found that 92% of the patients with DILE had demonstrable antihistone antibodies, contrasted with 33% of the patients in the DANA group (P less than 0.01). In those patients with antihistone antibodies (DILE versus DANA patients), there were no differences in the mean antibody titers. We conclude that the presence of antihistone antibodies is strong, statistically significant evidence that the symptoms of a given patient are due to drug-induced lupus erythematosus.