Impaired Neutrophil Function and Myeloperoxidase Deficiency in Myeloid Metaplasia

Abstract

The ability of neutrophils to phagocytose and kill Candida guilliermondii was investigated in 12 patients with myeloid metaplasia (MM). Following ingestion there was a considerable impairment in the ability of MM neutrophils to kill and digest Candida which was not explained by the very mild impairment in phagocytosis. Quantitative myeloperoxidase measurement revealed an overall deficiency of this enzyme in MM neutrophils and a highly significant correlation between low myeloperoxidase levels and impaired candidacidal activity. Neutrophils from patients with myeloid metaplasia showed a pattern of defective microbial killing, high alkaline phosphatase activity and low myeloperoxidase activity which was similar to that seen in severe infections and distinct from chronic granulocytic leukemia. The cells of 1 patient with particularly low myeloperoxidase and defective microbial killing were further studied both cytochemically and by EM. The azurophilic granules of this neutrophils were present in normal numbers and contained normal amounts of acid phosphatase but they lacked myeloperoxidase.