Neutrophil myeloperoxidase: a simple, reproducible technique to determine activity.

Neutrophil MPO deficiency has been rarely documented. This is because of the low incidence of infections in these individuals and the lack of use of various screening techniques which would detect them. Using the Hemalog D, we have identified one completely deficient and 18 partially deficient subjects. These subjects were studied by staining their peripheral blood smears for MPO and grading the intensity of the stain on 100 consecutive neutrophils (MPO score) as well as by chemically quantifying the MPO activity. There is an excellent correlation between MPO score and quantitated MPO activity. The MPO score is a simple semiquantitative method to estimate MPO activity.