title: Evidence for the activation of myeloperoxidase by f-Meth-Leu-Phe prior to its release from neutrophil granulocytes.
abstract: 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.
authors.affiliation: Department of Hematology and Oncology, Children's University Hospital, Tübingen, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Zipfel
authors.forename: T C
authors.initials: TC
authors.lastname: Carmine
authors.forename: C
authors.initials: C
authors.lastname: Gerber
authors.forename: D
authors.initials: D
authors.lastname: Niethammer
authors.forename: G
authors.initials: G
authors.lastname: Bruchelt
mesh_terms: D000328:Adult; D004789:Enzyme Activation; D005260:Female; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000494:pharmacology; D006801:Humans; D008297:Male; D008875:Middle Aged; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000494:pharmacology*; D009504:Neutrophils / Q000201:enzymology*; D009195:Peroxidase / Q000378:metabolism*
chemical_list: D009240:N-Formylmethionine Leucyl-Phenylalanine; D016178:Granulocyte-Macrophage Colony-Stimulating Factor; D009195:Peroxidase