Objective: Autoantibodies occur in the majority of patients receiving procainamide (PA) for more than one year. Slow acetylator status has been proposed to predispose to their development. We previously reported the results of serological evaluation of 52 asymptomatic patients receiving PA. The aims of this study were to follow these patients to determine the incidence of drug related lupus (DRL) and serologic changes in patients receiving longterm PA therapy; and to evaluate the possible effect of acetylator status on the development of PA autoimmunity.
Methods: Fifty-two patients receiving PA were reevaluated after a mean of 31.5 months. Antinuclear antibodies and antibodies to histones, dsDNA, and polyadenylic acid (PolyA) were assayed. Acetylator status was determined by phenotyping and genotyping methods. Five additional patients referred with a diagnosis of DRL were also evaluated.
Results: Autoantibodies were detected in the majority of patients still receiving PA and in some patients in whom PA had been discontinued. Slow acetylator status correlated with IgG antibodies to the H2A-2B dimer complex. Acetylator status did not correlate with PA dose. Seven of the 9 patients with PA related lupus were fast acetylators.
Conclusion: Most patients receiving PA have autoantibodies that may persist after discontinuation of PA. Despite persistently high frequency of autoantibodies the majority of these patients did not develop DRL. Slow acetylator status correlated with IgG antibodies to H2A-2B but was not a risk factor for the development of PA related lupus.