Quantitative slot-blot chemiluminescence assay for determination of myeloperoxidase from human granulocytes

Using slot blot, we show that myeloperoxidase (MPO), a constituent of azurophil granules of neutrophil polymorphonuclear leukocytes, can be measured quantitatively using a commercially available chemiluminescence kit, originally developed for detection of specific proteins on Western blots. MPO is determined through its ability to catalyze the oxidation of luminol, resulting in the emission of light which is recorded on a photographic film. The sensitivity of the method is high and allows MPO from less than 100 cells to be detected. This method was used to determine MPO in exudate fluid and in neutrophil fractions following disintegration and subcellular fractionation of the postnuclear supernatant on two-layer Percoll gradients.