Serologic evaluation of patients receiving procainamide

This controlled study examined the characteristics of serologic abnormalities in 52 patients receiving procainamide for cardiac arrhythmias, who had no symptoms of a connective tissue disease. Antinuclear antibodies occurred in 43 patients (83%). Significant elevation of antibody binding to single-stranded DNA (mean +/- SEM 30 +/- 2.6%), double-stranded DNA (13 +/- 1.1%), Z-DNA (optical density 0.54 +/- 0.06), and poly A (7.2 +/- 0.6%) was seen (P less than 0.001). Thirty-four patients (65.4%) had antibodies to total histones, most frequently, the H2A/2B dimer. IgG antibodies to H2A/2B correlated with the cumulative procainamide dose. One patient subsequently developed drug-related lupus.