| Abstract: |
The effect of purified recombinant human granulocyte-macrophage colony-stimulating factor (GM-CSF) on the oxidative metabolism of human peripheral blood granulocytes was investigated. The respiratory burst of granulocytes was assessed in individual cells by flow cytometry utilizing the oxidation of the nonfluorescent 2′,7′-dichlorofluorescein (DCFH) to the highly fluorescent DCF by hydrogen peroxide (H2O2). Treatment with GM-CSF caused granulocytes to produce H2O2 without addition of a second stimulus. The amount of H2O2 produced correlated with the concentration of GM-CSF administered. Also, GM-CSF did not prime the granulocytes for enhanced H2O2 production in response to N-formylmethionylleucyl-phenylalanine (f-MLP). Consecutive stimulation of granulocytes with GM-CSF and f-MLP resulted in additive production of H2O2. GM-CSF also induced granulocytes to release Superoxide anion (O2 -) in a dose-dependent manner, when the respiratory burst was assessed by a conventional cytochrome c reduction assay. In contrast to hydrogen Superoxide production, GM-CSF significantly (p < 0.001) enhanced f-MLP-stimulated release of superoxide anion over that expected from the additive effects of the two agonists. © 1992, Mary Ann Liebert, Inc. All rights reserved. |
