title: Up-regulation of granulocyte-macrophage colony-stimulating factor (GM-CSF) receptors in murine peritoneal exudate macrophages by both GM-CSF and IL-3.
abstract: Murine peritoneal exudate macrophages (PEM) display multiple CSF receptors. In this study, the expression of granulocyte-macrophage (GM)-CSF receptors in PEM was studied. PEM displayed over 5000 single type, high affinity GM-CSF receptors/cell with a Kd = 38 to 42 pM and an apparent molecular mass of 86,000 Da. Treatment of PEM with low, but not high, concentrations of recombinant murine (rMu) GM-CSF continuously for 24 h resulted in a marked up-regulation of GM-CSF receptors in PEM. A similar up-regulation of GM-CSF receptors also was detected in PEM cultures treated with rMuIL-3 (1-100 ng/ml) for 24 h or longer, regardless the doses of rMuIL-3 added in this case. Scatchard analysis of equilibrium binding showed that the enhanced binding activities in both cases were due to an increase in total number of GM-CSF receptors rather than changes in receptor affinity. Contrariwise, treatment with recombinant human macrophage-CSF (greater than 100-1000 ng/ml) partially inhibited the expression of GM-CSF receptors in PEM. Removal of rMuGM-CSF from culture medium 24 h after treatment led to a further up-regulation of GM-CSF receptors over a 4 to 24-h period, depending on the doses of initial treatment. On the other hand, removal of rMuIL-3 from culture medium after prolonged treatment did not result in further increase in GM-CSF receptors. The protein synthesis inhibitor cycloheximide abrogated GM-CSF receptor up-regulation induced by both rMuIL-3 and rMuGM-CSF, whereas actinomycin D inhibited only the second (8-24 h) phase of GM-CSF receptor up-regulation induced by exposure to high concentrations rMuGM-CSF (10 ng/ml). These findings suggest that rMuGM-CSF and rMuIL-3 up-regulate GM-CSF receptors in PEM in part through similar or identical metabolic pathways and provide further evidence of a close linkage between IL-3 and GM-CSF receptors.
authors.affiliation: Department of Internal Medicine, Wayne State University School of Medicine, Detroit, MI 48201.
authors.forename: K
authors.initials: K
authors.lastname: Fan
authors.forename: Q
authors.initials: Q
authors.lastname: Ruan
authors.forename: L
authors.initials: L
authors.lastname: Sensenbrenner
authors.forename: B D
authors.initials: BD
authors.lastname: Chen
mesh_terms: D000818:Animals; D003513:Cycloheximide / Q000494:pharmacology; D003609:Dactinomycin / Q000494:pharmacology; D005260:Female; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000494:pharmacology*; D007377:Interleukin-3 / Q000494:pharmacology*; D008024:Ligands; D016173:Macrophage Colony-Stimulating Factor / Q000494:pharmacology; D008264:Macrophages / Q000378:metabolism*; D008297:Male; D051379:Mice; D008809:Mice, Inbred C3H; D010529:Peritoneal Cavity / Q000166:cytology; D016187:Receptors, Granulocyte-Macrophage Colony-Stimulating Factor / Q000378:metabolism*; D011994:Recombinant Proteins / Q000494:pharmacology
chemical_list: D007377:Interleukin-3; D008024:Ligands; D016187:Receptors, Granulocyte-Macrophage Colony-Stimulating Factor; D011994:Recombinant Proteins; D003609:Dactinomycin; D016173:Macrophage Colony-Stimulating Factor; D016178:Granulocyte-Macrophage Colony-Stimulating Factor; D003513:Cycloheximide