Antiguanosine antibodies: a new marker for procainamide-induced systemic lupus erythematosus

Antinuclear antibodies are present in most patients receiving procainamide. To ascertain whether IgG antiguanosine antibodies are associated with the development of the symptoms of systemic lupus erythematosus, we compared the levels of these antibodies in the sera of 65 patients receiving procainamide: 18 with procainamide-induced symptoms and 47 asymptomatic patients. Antinuclear antibodies measured by immunofluorescence were present in the 18 patients with drug-induced symptoms but also in 24 asymptomatic patients. Similarly, elevated serum levels of antibodies to single-stranded DNA were found in 15 patients with symptoms and in 20 asymptomatic patients. In contrast, levels of IgG antiguanosine antibodies were elevated in 15 patients with drug-induced symptoms, but in only 3 asymptomatic patients. Antiguanosine antibodies binding to single-stranded DNA were found primarily in patients with arthritis, pleuritis, and pericarditis. These results suggest a strong association between IgG antiguanosine antibodies and major manifestations of procainamide-induced systemic lupus erythematosus.