title: Recombinant granulocyte-macrophage colony-stimulating factor down-regulates expression of IL-2 receptor on human mononuclear phagocytes by induction of prostaglandin E.
abstract: Recent studies have shown that normal human alveolar macrophages and blood monocytes, as well as HL-60 and U937 monocyte cell lines, newly express IL-2R after stimulation with rIFN-gamma or LPS. In addition, macrophages transiently express IL-2R in vivo during immunologically mediated diseases such as pulmonary sarcoidosis and allograft rejection. We therefore investigated in vitro factors that modulate macrophage expression of IL-2R. IL-2R were induced on normal alveolar macrophages, blood monocytes, and HL-60 cells using rIFN-gamma (24 to 48 h at 240 U/ml), and cells were cultured for an additional 12 to 24 h with rIL-2 (100 U/ml), recombinant granulocyte-macrophage CSF (rGM-CSF, 1000 U/ml), rGM-CSF plus indomethacin (2 X 10(-6) M), PGE2 (0.1 to 10 ng/ml), 1 X 10(-6) M levels of caffeine, theophylline, and dibutyryl cyclic AMP, or medium alone. IL-2R expression was quantitated by cell ELISA (HL-60 cells) or determined by immunoperoxidase staining (alveolar macrophages, blood monocytes, and HL-60 cells), using anti-Tac and other CD25 mAb. PGE production was assayed by RIA. We found greater than 95% of alveolar macrophages, monocytes, and HL-60 cells expressed IL-2R after rIFN-gamma treatment and remained IL-2R+ in the presence of IL-2R or medium alone. By comparison, greater than 95% of cells induced to express IL-2R became IL-2R- after addition of rGM-CSF, and the culture supernatants from GM-CSF-treated cells contained increased levels of PGE. This inhibition of macrophage IL-2R expression by rGM-CSF was blocked by indomethacin, and IL-2R+ macrophages became IL-2R- after addition of PGE2 alone. These findings indicate GM-CSF down-regulates IL-2R expression by human macrophages via induction of PGE synthesis. Moreover, a similar down-regulation of IL-2R expression was seen after stimulation with caffeine, theophylline, or dibutyryl cyclic AMP. Hence, GM-CSF, PGE, and other pharmacologic agents that act to increase intracellular levels of cAMP may play a modulatory role, antagonistic to that of IFN-gamma on cellular expression of IL-2R by human inflammatory macrophages in vivo.
mesh_terms: D002460:Cell Line; D002462:Cell Membrane / Q000502:physiology; D003115:Colony-Stimulating Factors / Q000494:pharmacology*; D015232:Dinoprostone; D004797:Enzyme-Linked Immunosorbent Assay; D016178:Granulocyte-Macrophage Colony-Stimulating Factor; D006133:Growth Substances / Q000494:pharmacology*; D006801:Humans; D007124:Immunoenzyme Techniques; D066298:In Vitro Techniques; D007213:Indomethacin / Q000494:pharmacology; D008264:Macrophages / Q000502:physiology*; D009000:Monocytes / Q000502:physiology*; D011458:Prostaglandins E / Q000096:biosynthesis*; D011650:Pulmonary Alveoli / Q000166:cytology; D011971:Receptors, Immunologic / Q000378:metabolism*; D015375:Receptors, Interleukin-2; D011994:Recombinant Proteins / Q000494:pharmacology
chemical_list: D003115:Colony-Stimulating Factors; D006133:Growth Substances; D011458:Prostaglandins E; D011971:Receptors, Immunologic; D015375:Receptors, Interleukin-2; D011994:Recombinant Proteins; D016178:Granulocyte-Macrophage Colony-Stimulating Factor; D015232:Dinoprostone; D007213:Indomethacin