Quinidine-induced lupus erythematosus.

A 60-year-old white man presented with a syndrome of fever, polyarthritis, pleurisy, and lymphopenia, and had a positive antinuclear antibody test (after 5 months of quinidine therapy). Quinidine-induced antinuclear autoantibodies were of the IgM and IgG classes and were directed mainly to nuclear histones, predominantly histones H1 and H2B. Antibodies to native DNA and nonhistone nuclear antigens were not seen during the patient's clinical course. Upon withdrawal of quinidine therapy, the patient had prompt improvement of clinical symptoms followed by a gradual resolution of serologic abnormalities.