Preservation of basophils in dapsone-induced agranulocytosis suggests a possible pathogenetic role for leucocyte peroxidases.

We describe a hitherto unreported laboratory observation, namely the selective preservation of basophils, in a case of severe dapsone-induced agranulocytosis. Dapsone is known to be metabolised by peroxidases to nitroso derivatives in non-hemopoietic cells where these can in turn act as haptens. Our observation that basophils are selectively spared in this syndrome supports the hypothesis that leucocyte peroxidases function in a similar way to facilitate the pathogenesis of this form of agranulocytosis in susceptible individuals.