Antinuclear antibodies as indicators for the procainamide-induced systemic lupus erythematosus-like syndrome and its clinical presentations.

Fifty patients on a regimen of procainamide were studied in regard to the association between antinuclear antibodies (ANA) and the development of drug-induced systemic lupus erythematosus (SLE)-like syndrome. Four groups were identified: Group 1 was ANA-positive, with clinical manifestations (serologic and clinical findings); Group 2 was ANA-positive, without clinical manifestations (serologic findings only); Group 3 was ANA negative (no patients with clinical manifestations); and Group 4 had SLE persisting after discontinuance of procainamide. The leukocyte-specific ANA (LSANA) patterns were predominant, with peripheral LSANA confined to Groups 1 and 4. Furthermore, the titer of the homogeneous LSANA, to which peripheral LSANA converts on dilution, was clinically significant. A homogeneous LSANA titer of 160 or greater was seen essentially only in patients with clinical manifestations of the SLE-like syndrome. Serial ANA determinations are therefore necessary to monitor patients receiving procainamide.