Histone reactivity of drug‐induced antinuclear antibodies

Anti‐histone antibodies were measured in a group of patients with drug‐induced lupus erythematosus and in asymptomatic patients with drug‐induced antinuclear antibodies (DANA). Anti‐histone antibodies were found in the majority of drug‐induced lupus patients. DANA patients had lower titers of ANA and no detectable anti‐histone activity. Longitudinal studies of the drug‐induced lupus patients showed a gradual fall in the ANA and anti‐histone titers. Our data suggest that the immune response in the drug‐induced lupus patients is similar to but more intense than that seen in the DANA patients. Possible factors altering the immune response in these 2 groups are discussed.