Evidence for the activation of myeloperoxidase by f-Meth-Leu-Phe prior to its release from neutrophil granulocytes

Biochem Biophys Res Commun. 1997 Mar 6;232(1):209-12. doi: 10.1006/bbrc.1997.6257.


Activity and release of myeloperoxidase (MPO) was measured in heparinized whole blood samples after activation of neutrophil granulocytes by the chemoattractant N-formyl-methionyl-leucyl-phenylalanine (fMLP) using two different methods: (i) by determination of the amount of MPO released into the blood plasma using a MPO enzyme-immunoassay, and (ii) simultaneously, by measuring the remaining activity within the neutrophils by flow cytometry using the Bayer Technicon H3. Although a part of MPO was released immediately after addition of fMLP, remaining MPO activity within the neutrophils surprisingly increased during the first minutes after incubation. Subsequently, MPO activity dropped due to a continuous release of MPO. In addition to fMLP, granulocyte-macrophage colony stimulating factor (GM-CSF) enhanced MPO activity in neutrophils. These results indicate that MPO is present in resting granulocytes in an inactive or only partially active form and is activated by fMLP and GM-CSF.

MeSH terms

  • Adult
  • Enzyme Activation
  • Female
  • Granulocyte-Macrophage Colony-Stimulating Factor / pharmacology
  • Humans
  • Male
  • Middle Aged
  • N-Formylmethionine Leucyl-Phenylalanine / pharmacology*
  • Neutrophils / enzymology*
  • Peroxidase / metabolism*


  • N-Formylmethionine Leucyl-Phenylalanine
  • Granulocyte-Macrophage Colony-Stimulating Factor
  • Peroxidase