NEW APPROACHES TO THE DETECTION OF MYELOPEROXIDASE DEFICIENCY

  • 1 January 1982
    • journal article
    • research article
    • Vol. 60  (2) , 323-327
Abstract
Family studies on myeloperoxidase (MPO) deficiency were carried out by quantitating the peroxidase activity of granulocyte preparations with 3 methods: guaiacol peroxidation, alanine decarboxylation and spectroscopic analysis. The guaiacol assay failed to show a definite pattern of inheritance in 2 families with MPO-deficient subjects. The granulocytes of 3 histochemically MPO-negative subjects had a peroxidase activity either half or even higher than that of control subjects. The peroxidase activity of these granulocyte preparations in these 3 subjects showed a positive correlation to the number of eosinophils. The possibility then considered was that eosinophils may have obscured the true pattern of inheritance in this assay. Two other methods of MPO assay which were not influenced by the presence of eosinophil peroxidase (EPO) were devised. One was based on the ability of MPO, but not EPO, to catalyze decarboxylation of L-alanine in the presence of Triton X-100, and the other relied on the different spectral properties of the 2 peroxidases. The results obtained with these 2 methods were strictly comparable, allowed detection of both totally and partially MPO-deficient subjects, differed profoundly from those obtained with the guaiacol method when eosinophil-containing granulocyte preparations were used, and revealed a pattern of autosomal recessive inheritance in the 2 families studied. The results of the 3 methods were comparable when eosinophil-free granulocyte preparations were assayed. Failure to show a pattern of inheritance in some instances of primary MPO deficiency or deviations from the autosomal recessive mode of transmission of this defect may be attributed to interference by EPO. Peroxidase assay methods not subject to EPO interference, such as the 2 described in this article, may be used, particularly in the detection of heterozygote subjects for MPO deficiency in the presence of high eosinophil counts.