Acquired myeloperoxidase deficiency and recurrent infections in a patient with acute myelomonocytic leukemia.

Acquired myeloperoxidase deficiency has been reported in several hematological malignancies. The clinical course of a patient with acute myelomonocytic leukemia is described which was characterized by staphylococcal infections prior to therapy and again during a period of relapse. Neutropenia was not a feature of these two periods but in vitro studies revealed decreased bacterial killing capacity and decreased neutrophil myeloperoxidase activity. Infectious complications were not observed during drug-induced remission when bacterial killing capacity and myeloperoxidase activity were improved toward normal. These observations suggest that the myeloperoxidase deficient neutrophils were derived from leukemic progenitors.