Myeloperoxidase deficiency: an epidemiological study and flow-cytometric detection of other granular enzymes in myeloperoxidase-deficient subjects.

MPO deficiency, as first studied in the 1960s, has been recorded with increasing frequency, following the introduction of the automated cytochemical count into clinical routine. However, with regard to the diseases correlated to MPO deficiency, no exact data on the frequency of co-existence have been recorded. Moreover, the question remains whether or not a further deficiency of other granular enzymes co-exists, especially with regard to acquired MPO deficiency. In order to answer these questions, an epidemiological study of more than 70,000 unselected patients was performed; the resulting prevalence of MPO deficiency was 0.15%. Within this patient group the intercellular content of elastase-like protease (ELP) and lactoferrin was measured semiquantitatively in a flow cytometer by means of indirect immunofluorescence staining. The frequency of coinciding diseases did not differ from the frequency of diseases in the hospital patients in general. The flow-cytometric studies revealed a normal content of ELP and lactoferrin in one group and a reduced content in another, suggesting the inherited form in the former and acquired MPO deficiencies in the latter group and thus indicating that differing mechanisms characterize the two forms of MPO deficiency. Nevertheless, we do not suggest distinguishing between acquired and inherited deficiencies solely with this technique. Instead, molecular-biologic and/or genetic methods should be referred to.