Infrequency of anticentromere antibody in patients without systemic sclerosis and without Raynaud's phenomenon

Abstract

Reply To the Editor:We appreciate Dr. Emery's comments. We are aware of 3 published studies of drug-induced lupus that include results of HLA typing (1-3). An increased frequency of the HLA-DR4 antigen was noted in only 1 of 2 studies of hydralazine-induced lupus. This association was not observed in the 1 study of procainamide-induced lupus. The frequency of the HLA-DR6Y antigen was increased among procainamide-treated patients who developed a lupus syndrome, but not among those who developed antinuclear antibodies without symptoms of lupus (3). (The absence of an HLA association in the appearance of antinuclear antibodies would be expected considering that almost all individuals who take procainamide develop such antibodies.) It appears that more studies are required before a specific genetic predisposition-defined by the HLA antigen system-for the development of drug-induced lupus can be confirmed.Drug-induced lupus and spontaneous systemic lupus erythematosus differ in their clinical and serologic features, although similarities in the 2 syndromes suggest that a common pathogenetic mechanism cannot be excluded. Our study indicates that the slow acetylator phenotype, which is found in more than 95% of patients with hydralazine-induced lupus (1,4,5), is not increased in frequency among patients with spontaneous lupus. Since spontaneous lupus is a heterogeneous disorder, the possibility remains that there may be a small proportion of patients in whom a slow acetylator phenotype might predispose to the induction of a lupus syndrome after exposure to environmental aromatic amines or hydrazines (6).