Effects on extra- and intracellularly localized, chemoattractant-induced, oxygen radical production in neutrophils following modulation of conditions for ligand-receptor interaction.
Results obtained with the luminol-dependent chemiluminescence (CL) technique show that with this technique, generation of oxygen radicals from an extra- as well as from an intracellular source is quantified. This investigation was performed in order to study the relationship between intra- and extracellularly generated radicals in human granulocytes stimulated with the chemoattractant formyl-methionyl-leucyl-phenylalanine (FMLP). A difference in time course between extra- and intracellular CL was observed. The extracellular response reached a maximum value after 1-2 min, whereas the intracellular response reached a maximum value after 5-7 min. The ED50 values for the two responses were the same, whereas the onset time was a little longer for the intracellular response. Both high and low concentrations of FMLP gave rise to CL. However, the ratio between the extra- and the intracellular response differed depending on the concentration of FMLP; the ratio was decreased at low concentrations of FMLP. The same type of change was obtained when the ligand-receptor ratio was decreased through modulation of the number of exposed receptors. The ratio between extra- and intracellular activities was also changed by cytochalasin B, removal of Ca2+, or removal of Na+. The role of the extra- and intracellular oxygen radical production as well as possible regulatory mechanisms are discussed.
Dahlgren
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Department of Medical Microbiology, University of Linköping, Sweden.
D006801:Humans; D006861:Hydrogen Peroxide / Q000378:metabolism*; D008024:Ligands; D008163:Luminescent Measurements; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000494:pharmacology; D009504:Neutrophils / Q000187:drug effects / Q000378:metabolism*; D011956:Receptors, Cell Surface / Q000378:metabolism; D013481:Superoxides / Q000378:metabolism*; D013997:Time Factors
D008024:Ligands; D011956:Receptors, Cell Surface; D013481:Superoxides; D009240:N-Formylmethionine Leucyl-Phenylalanine; D006861:Hydrogen Peroxide