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Query: UNIPROT:P04141 (granulocyte-macrophage colony-stimulating factor)
 6,790 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Platelet-activating factor (1-O-alkyl-2-acetyl-sn-glycerol-3-phosphocholine; PAF) enhances the release of newly synthesized PAF as measured by [3H]acetate incorporation into PAF in human neutrophils. The response was dose-dependent, rapid, transient, and inhibitable by the PAF antagonist BN-52021. The non-metabolizable bioactive PAF analogue (C-PAF) but not lyso-PAF enhances the release of newly synthesized PAF. Newly synthesized PAF was also released after stimulation of these cells with fMet-Leu-Phe. The human granulocyte-macrophage colony-stimulating factor potentiates the stimulated release of PAF. The intracellular calcium chelator BAPTA inhibits the rise of [Ca2+]i and the release of PAF but not the Na+/H+ antiport activity. PAF release, but not the rise in the intracellular concentration of free calcium, was inhibited in pertussis toxin-treated neutrophils stimulated with PAF. The release of PAF in pertussis toxin-treated cells was also inhibited in cells stimulated with fMet-Leu-Phe or opsonized zymosan. These results suggest that functional pertussis toxin-sensitive guanine nucleotide regulatory protein and/or one or more of the changes produced by phospholipase C activation are necessary for PAF release produced by physiological stimuli. It appears that PAF release requires a coordinated action of receptor-coupled G-proteins, calcium, and other parameters.
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PMID:Calcium is necessary but not sufficient for the platelet-activating factor release in human neutrophils stimulated by physiological stimuli. Role of G-proteins. 251 17

Granulocyte-macrophage colony-stimulating factor, GM-CSF, potentiates superoxide generation produced by human neutrophils stimulated with fMet-Leu-Phe and platelet-activating factor, PAF, but not by phorbol 12-myristate 13-acetate (PMA) or opsonized zymosan. The potentiation is greatest in fMet-Leu-Phe-stimulated cells. This indicates that the actions of only certain receptors are potentiated by GM-CSF. Incubation of the cells with the protein kinase inhibitor H-7 or with the protein synthesis inhibitor cyclohexamide before the addition of GM-CSF does not affect the observed potentiation. The rationales behind these studies are to examine the roles of protein kinase C and protein synthesis in the action of GM-CSF. The data suggest that neither protein kinase C nor protein synthesis is necessary for GM-CSF action. On the other hand, no potentiation can be seen in the presence of cytochalasin B. Unlike intact cells, GM-CSF does not enhance superoxide production by cytoplasts stimulated with fMet-Leu-Phe. The rationale behind the use of cytoplasts is to examine the role of granules and/or nucleus in GM-CSF action, and the data indicate that one or more of these two components is necessary for the priming effect of GM-CSF. The amount of actin associated with the cytoskeleton under control of fMet-Leu-Phe-stimulated condition is the same in normal and GM-CSF-treated human neutrophils. Botulinum D toxin ADP-ribosylates a protein with a molecular weight of 22 kDa. This ribosylation is reduced in homogenates obtained from cells pretreated with botulinum D toxin or GM-CSF. Botulinum D toxin does not affect the basal or the fMet-Leu-Phe-induced rise in the intracellular concentration of free calcium in human neutrophils. GM-CSF also increases the rise in intracellular concentration of free calcium in human neutrophils stimulated with PAF or fMet-Leu-Phe. The increases are inhibited by pertussis toxin. Several important conclusion can be drawn from these data. 1) GM-CSF potentiates the rise in Ca2+i produced by PAF and fMet-Leu-Phe, and these potentiations are inhibited in pertussis-toxin-treated cells. 2) GM-CSF does not prime cytoplasts to stimulation by fMet-Leu-Phe. This suggests that the granules and/or nucleus are necessary for the priming action. 3) The priming by GM-CSF is not mediated by the H-7-sensitive protein kinase C, botulinum D-sensitive G-protein, or protein synthesis.
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PMID:Effect of granulocyte-macrophage colony-stimulating factor on superoxide production in cytoplasts and intact human neutrophils: role of protein kinase and G-proteins. 254 9

Neonatal granulocytes are recognized to have functional defects which are thought to be important in the increased susceptibility to infection in the neonate. Recombinant human granulocyte-macrophage colony-stimulating factor (rhGM-CSF), a member of a family of glycoproteins essential for the in vitro survival, proliferation, and differentiation of hematopoietic progenitor cells, has been shown to enhance the functional capabilities of adult granulocytes. This study tested the effects of rhGM-CSF on the locomotion, superoxide generation, phagocytosis, bactericidal activity, and membrane depolarization responses of cord blood granulocytes. Concentrations of rhGM-CSF between 100 and 1 pM significantly enhanced the leading front of cord blood granulocyte locomotion. The mean distance migrated by the cell population and the number of cells responding to the chemoattractant were also significantly enhanced in cord blood granulocytes treated with 1 pM rhGM-CSF. Superoxide anion production was significantly enhanced in cord blood granulocytes stimulated with fMLP after a 30- or 60-min exposure to 100 pM rhGM-CSF. However, this enhancing effect was not observed in cells incubated with rhGM-CSF for 2 h before formyl-methionine-leucine-phenylalanine stimulation. Phagocytosis, bactericidal activity, and membrane depolarization responses of cord blood granulocytes were not affected by exposure to rhGM-CSF. These findings demonstrate that selected cord blood granulocyte functions are enhanced by in vitro exposure to rhGM-CSF. Whether these in vitro observations have in vivo significance await further study.
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PMID:The effects of recombinant human granulocyte-macrophage colony stimulating factor on in vitro cord blood granulocyte function. 254 92

The regulation of mature human neutrophil function by recombinant human granulocyte-macrophage colony-stimulating factor (rH GM-CSF) was studied. Preincubation of neutrophils with this CSF did not stimulate superoxide anion directly but enhanced the subsequent release of superoxide anion in response to stimulation with the bacterial product formylmethionylleucyl-phenylalanine (f Met-Leu-Phe). Enhanced superoxide anion production was evident by 5 min and reached a plateau at 30 min. In contrast, neutrophils preincubated with rH GM-CSF exhibited reduced chemotaxis under agarose in response to a gradient of f Met-Leu-Phe. The inhibition of neutrophil migration was dependent on the dose of rH GM-CSF and exhibited a time-course similar to the effect on superoxide production. Binding studies of f Met-Leu-[3H]Phe to purified human neutrophils revealed heterogeneous binding to unstimulated cells. Two affinity components were identified. The high-affinity component consisted of approximately 2000 sites/cell and had an average Kd of 4 +/- 2 nM (n = 6). The low-affinity component consisted of approximately 40,000 sites/cell and had an average Kd of 220 +/- 130 nM (n = 6). rH GM-CSF caused conversion to a linear Scatchard plot showing no significant change in total binding sites but a single Kd of 30 +/- 10 nM. These data indicate that rH GM-CSF may influence neutrophil responses to f Met-Leu-Phe by regulating the affinity of f Met-Leu-Phe receptors.
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PMID:Recombinant human granulocyte-macrophage colony-stimulating factor (rH GM-CSF) regulates f Met-Leu-Phe receptors on human neutrophils. 284 55

Human granulocyte-macrophage colony-stimulating factor (GM-CSF) has been shown to inhibit migration of mature granulocytes and to enhance their antibody-dependent cellular cytotoxicity. We found that human recombinant GM-CSF also enhanced granulocyte-granulocyte adhesion and increased by two- to threefold the surface expression of Mo1 and LeuM5 (P150, 95), two members of a family of leukocyte adhesion molecules (Leu-CAM). Increased Mo1 surface expression occurred within 15 min at 37 degrees C and was maximal at the migration inhibitory concentration of 500 pM. One-half maximal rise in the expression of Mo1 on the cell surface occurred at 5 pM. The chemotactic peptide f-Met-Leu-Phe produced a comparable rise in surface Mo1 with one-half maximal expression occurring at 7 nM. Both GM-CSF and f-Met-Leu-Phe produced optimal granulocyte-granulocyte adhesion at 500 pM and 100 nM, respectively. This adhesion-promoting effect induced by either stimulus was inhibited by a mouse monoclonal antibody directed against Mo1 antigen. These data indicate that GM-CSF promotes cell-to-cell adhesion, presumably through enhanced expression of leukocyte adhesion molecules. This mechanism may explain, in part, the known effects of GM-CSF on the function of mature granulocytes.
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PMID:Human recombinant granulocyte-macrophage colony-stimulating factor increases cell-to-cell adhesion and surface expression of adhesion-promoting surface glycoproteins on mature granulocytes. 309 Jan 6

Human granulocyte-macrophage colony-stimulating factor (GM-CSF) is an in vitro and in vivo stimulator of human bone marrow myelomonocytic precursor cells and mature granulocyte and macrophage effector cells. We have compared the effect of GM-CSF on the synthesis of 5-lipoxygenase products induced by the chemotactic peptide fMet-Leu-Phe and the calcium ionophore A23187 in human neutrophils. Although GM-CSF alone did not stimulate detectable synthesis of products of the 5-lipoxygenase pathway, pre-incubation of neutrophils with 200 pM GM-CSF for 1 hour at 23 degrees C enhanced synthesis of leukotriene B4, its all-trans isomers and omega-oxidation products, and 5-hydroxyeicosatetraenoic acid in response to both the calcium ionophore A23187 (1.5 microM), and the chemotactic peptide fMet-Leu-Phe (0.1 microM). This priming effect of GM-CSF was maximal after a 60 min incubation at 23 degrees C, or after a 30 min preincubation at 37 degrees C. The effect of GM-CSF was maximal using a concentration of 1 nM. Enhancement of the leukotriene synthesis stimulated by A23187 was only observed when the cells were stimulated by the ionophore for periods of 3 minutes or less. In contrast, the enhancing effect of GM-CSF was still apparent when cells were exposed to fMet-Leu-Phe for as long as 15 minutes. Furthermore, the enhancing effect of GM-CSF was ablated when neutrophils were stimulated with A23187 and exogenous arachidonic acid. However, co-addition of exogenous arachidonic acid with fMet-Leu-Phe did not entirely mask the effect of GM-CSF. Possible mechanisms of action of GM-CSF are discussed.
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PMID:Characterization of the priming effects of human granulocyte-macrophage colony-stimulating factor on human neutrophil leukotriene synthesis. 314 64

Normal human bone marrow mononuclear cells were fractionated by differential adherence, immunomagnetic separation, and fluorescence-activated cell sorting (FACS). The resultant fractionated cells were cultured in semisolid medium to monitor the presence of BFU-E, Mix-CFC, and nonerythroid CFC. Two populations of cells were recovered on the basis of binding by the monoclonal antibody (MoAb) RFB-1. One of these populations contained BFU-E that were stimulated only by erythropoietin (Epo), whereas the second population contained BFU-E responsive to Epo, Epo and recombinant human granulocyte-macrophage colony-stimulating factor (rHGM-CSF), or Epo and human placental-conditioned medium (HPCM). Prior enrichment of clonogenic cells by removal of adherent and Leu-M3+ve, Leu-4+ve, Leu-7+ve, B1+ve, WEMG1+ve, and Glycophorin A+ve cells, followed by FACS fractionation on the basis of RFB-1 binding, consistently resulted in recoveries of BFU-E, Mix-CFC, and nonerythroid CFC of greater than 100% (up to 800%). These procedures also resulted in enrichment of up to 200-fold and frequencies of 1:6 for BFU-E, 1:5 for CFC, and 1:130 for Mix-CFC.
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PMID:Fractionation of subsets of BFU-E from normal human bone marrow: responsiveness to erythropoietin, human placental-conditioned medium, or granulocyte-macrophage colony-stimulating factor. 327 56

For direct studies of growth control, a method was developed to purify viable human megakaryocytes to homogeneity from routine normal bone marrow aspirates. An initial separation of marrow over a 1.050 g/mL Percoll density cut was used to enrich megakaryocytes. After washing, the cells were specifically labeled with a fluoresceinated monoclonal antibody or F(ab')2 fragment to the platelet glycoprotein (GP) IIb/IIIa complex. Megakaryocytes were selectively sorted by using Becton Dickinson FACStar flow cytometer on the basis of a fluorescence intensity greater than 50-fold that of control cells. To increase resolution and purity the sorting rate was adjusted to one cell in 13 formed drops, and negative events that coincided with positive ones were aborted. Two thirds of the isolated cells were large, morphologically recognizable megakaryocytes with a forward light scatter fourfold that of the main cell population. Microscopic examination showed these cells to be greater than or equal to 98% megakaryocytes with a diameter of 20 to 46 microns and a ploidy range of 2N to 64N with a mode of 16N. The small highly fluorescent cells were 10 to 21 microns in diameter, and their ploidy range from 2N to 32N with main ploidy classes of 2N and 4N. The majority of these small cells also positively reacted with monoclonal antibody to platelet GPIb. The isolated cells were cultured in either Iscove's or leucine, lysine-deficient RPMI 1640 medium with 10% human plasma. The cells were maintained in culture more than three days and were capable of synthesis of both DNA and protein as assessed by radiolabeled thymidine and amino acid incorporation. Moreover, the isolated megakaryocytes were capable of responding to recombinant granulocyte-macrophage colony-stimulating factor. The data show that human megakaryocytes can be purified from routine marrow aspirates on the basis of a lineage marker and that they are capable of growth in vitro.
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PMID:Purification of human megakaryocytes by fluorescence-activated cell sorting. 331 39

Human granulocyte-macrophage colony-stimulating factor (GM-CSF) modulates the function of mature neutrophils by priming for enhanced chemotaxis and oxidative metabolism in response to N-formyl-methionyl-leucyl-phenylalanine (f-Met-Leu-Phe). Our studies establish a relationship between f-Met-Leu-Phe receptor number and affinity and neutrophil chemotaxis and oxidative metabolism. A brief (5- to 15-min) exposure to physiologic concentrations of GM-CSF (10 pM to 100 pM) enhances f-Met-Leu-Phe-induced neutrophil chemotaxis by 85%, correlating with a rapid threefold increase (46,000/cell to 150,000/cell) in high-affinity neutrophil f-Met-Leu-Phe receptors. More prolonged incubation (1 to 2 hr) of neutrophils with GM-CSF is accompanied by a change to low-affinity f-Met-Leu-Phe receptors (Kd = 29 nM to Kd = 99 nM) concomitant with priming for enhanced neutrophil oxidative metabolism. Moreover, enhanced chemotactic responses to f-Met-Leu-Phe are no longer evident after more prolonged incubation of neutrophils with GM-CSF. These results show that a single lymphokine (GM-CSF) induces sequential changes in neutrophil f-Met-Leu-Phe receptor number and affinity that may enhance different physiologic responses.
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PMID:Biosynthetic human GM-CSF modulates the number and affinity of neutrophil f-Met-Leu-Phe receptors. 349 Nov 42

Adherence of human neutrophils to plastic, fibronectin, or collagen-coated surfaces modifies their response to several agonists including granulocyte-macrophage colony-stimulating factor (GM-CSF), tumor necrosis factor alpha (TNF-alpha), and fMet-Leu-Phe, permitting them to trigger superoxide anion (O2-) release, which they are unable to do as cells in suspension. Adherence of neutrophils causes a slight decrease in the basal level of tyrosine phosphorylation compared with that of suspended cells. The addition of GM-CSF, however, brings all proteins to a level of phosphorylation at least equal to that seen in suspended cells. In the case of a 130-kDa (p130) and a 42-kDa (p42) protein, the increase in tyrosyl phosphorylation in response to GM-CSF challenge is clearly larger in adherent than in suspended cells (6- and 4-fold increases for p130 and p42, respectively, in adherent cells vs. 1.7- and 2.1-fold in suspended cells). This is even more patient in the case of collagen-coated plates (9.4-fold increase for p42). Therefore, once neutrophils attach to surfaces, they become primed and respond to GM-CSF with greater potency than when they are in suspension. By Western blot analysis with anti-MAP kinase antibodies, we demonstrate that p42 is one member of the mitogen-activating protein kinase, namely the p42MAPK. The tyrosyl phosphorylation of p42MAPK is elevated in GM-CSF-treated adherent neutrophils in a time-dependent fashion as measured by the formation of a doublet composed of the phospho (or activated) form and the dephospho (or inactive) form of MAP kinase. MAP kinase activation and tyrosine phosphorylation are inhibited by tyrosine kinase inhibitors genistein and tyrphostin-23. Our results indicate that adherence acts to prime neutrophils for enhanced functionality and that tyrosine phosphorylation is involved in this process.
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PMID:Priming of tyrosine phosphorylation in GM-CSF-stimulated adherent neutrophils. 772 26


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