Gene/Protein Disease Symptom Drug Enzyme Compound
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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)

The target cell specificity of interleukin-3 (IL-3) was examined by flow cytometric analysis of IL-3 receptor (IL-3R) expression on rhesus monkey bone marrow (BM) cells using biotinylated IL-3. Only 2% to 5% of unfractionated cells stained specifically with the biotinylated IL-3 and most of these cells were present within the CD34+ subset. IL-3Rs were detected on small CD34dull/RhLA-DRbright/CD10+/CD27+/CD2-/++ +CD20- cells, which probably represent B-cell precursors. IL-3R+ CD34- BM cells, which were detected at low frequencies, consisted of small CD20dull/surface-IgM+/RhLA-DR+ cells. These cells represented immature B lymphocytes, whereas CD20bright mature B cells were IL-3R-. The highest IL-3R levels were detected on CD34dull/RhLA-DRbright blast-like cells. These cells differentiated into monocytes, neutrophils, and basophils after IL-3 and/or granulocyte-macrophage colony-stimulating factor (GM-CSF) stimulation in vitro. The CD34bright/IL-3R- subset contained all clonogenic erythroid and myeloid progenitors (burst-forming unit-erythroid and colony-forming unit-culture), whereas CD34bright/IL-3Rdull cells differentiated into monocytes, neutrophils, and erythroid cells after shorter culture periods. This finding showed that IL-3R expression increases during monocyte and granulocyte differentiation. Results of three-color experiments indicated that IL-3Rs are expressed on CD34bright/RhLA-DRbright cells as well as on CD34bright/RhLA-DRdull cells, with the latter population expression approximately twofold to threefold lower IL-3R levels. A large fraction (> 30%) of single-cell/well-sorted CD34bright/RhLA-DRdull cells formed multilineage colonies after 2 to 4 weeks of stimulation with IL-3, GM-CSF, Kit ligand, and IL-6. Individual colonies contained cells that still expressed CD34 as well as differentiated monocytes, granulocytes, and erythroid cells. These results confirmed that the CD34bright/RhLA-DRdull subset was enriched for immature, multipotent progenitor cells, whereas the CD34bright/RhLA-DRbright population mainly contained lineage-committed precursors. The results are consistent with the concept that IL-3Rs are induced at very early stages of hematopoiesis, as identified by high expression of CD34 and low expression of RhLA-DR. IL-3R expression continues to be low during differentiation into lineage-committed progenitors; gradually increases on differentiating progenitor cells for B cells, granulocytes, monocytes, and, possibly also, erythrocytes; but finally declines to undetectable levels during terminal differentiation into mature cells of all lineages in peripheral blood, with the exception of basophils.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Differential expression of receptors for interleukin-3 on subsets of CD34-expressing hematopoietic cells of rhesus monkeys. 754 69

To understand the hematopoietic and nonhematopoietic responses to interleukin-3 (IL-3), expression of cell-surface IL-3 receptors (IL-3R) was examined on bone marrow (BM) cells and peripheral blood (PB) cells of rhesus monkeys during the course of in vivo IL-3 treatment. Whereas IL-3R expression is low in untreated monkeys, IL-3 administration led to a gradual increase in both low- and high-affinity binding sites for IL-3. This increase reflected the total number of cells expressing IL-3Rs, as detected by flow cytometry using biotinylated IL-3. Most of these IL-3R+ cells in both BM and PB could be characterized as basophilic granulocytes that contained high levels of histamine. In contrast to the effect on these differentiated cells, IL-3 administration did not significantly alter the low level IL-3R expression on immature, CD34+ cells. Further flow cytometric analysis using biotinylated growth factors showed that the IL-3R+ basophils also expressed receptors for granulocyte-macrophage colony-stimulating factor (GM-CSF), but not for IL-6 or Kit ligand. These findings indicated that the IL-3R+ cells included neither monocytes, which express GM-CSFRs and IL-6Rs abundantly, nor mast cells, which express c-kit. By combining flow cytometric and Scatchard data, it was calculated that the basophils contain as many as 1 to 2 x 10(3) high-affinity IL-3Rs and 15 to 30 x 10(3) low-affinity sites. The finding that in vivo IL-3 treatment leads to the production of large numbers of cells that express high levels of IL-3R and are capable of producing histamine provides an explanation for the often severe allergic reactions that occur during prolonged IL-3 administration. It also indicates that IL-3, in addition to its direct effects on hematopoietic cells, may also stimulate hematopoiesis through the release of secondary mediators such as histamine by IL-3-responsive mature cells.
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PMID:Interleukin-3 treatment of rhesus monkeys leads to increased production of histamine-releasing cells that express interleukin-3 receptors at high levels. 754 70

Stimulatory cytokines, including granulocyte-macrophage colony-stimulating factor (GM-CSF) and steel factor (SLF), act in a synergistic manner to stimulate the growth of hematopoietic progenitor cells, an effect also demonstrated for the growth factor-dependent human hematopoietic cell line MO7e. While little is known about the mechanisms responsible for mediating synergistic interactions of cytokines, Raf-1, a component of the MAP kinase signaling pathway, is thought to play a role in the stimulatory response evoked by several cytokines, including SLF and GM-CSF. Interferon-inducible protein-10 (IP-10) and macrophage inflammatory protein-1 alpha (MIP-1 alpha) are members of the chemokine family of suppressive cytokines. Prior exposure of hematopoietic cells to chemokines, including IP-10 and MIP-1 alpha, inhibits the synergistic action of growth factors on stimulating cell proliferation. We report that treatment of MO7e cells with the combination of GM-CSF and SLF directly stimulates statistically significant synergistic increases in the phosphorylation and activation of Raf-1 kinase, and in cellular protein synthesis levels. Pretreatment of MO7e cells with IP-10 or MIP-1 alpha blocked synergistic growth factor action, resulting in statistically significant suppression of cell proliferation, protein synthesis, and Raf-1 phosphorylation and activation. IP-10 and MIP-1 alpha treatment also evoked significant increases in intracellular cAMP levels. Pretreatment of cells with agents which serve to raise intracellular cAMP levels, or with cAMP analogs inhibited the synergistic actions of GM-CSF and SLF in a manner similar to IP-10 and MIP-1 alpha. In addition, treatment of cells with a potent inhibitor of cAMP-dependent protein kinase A blocked the suppressive action of MIP-1 alpha and IP-10 on Raf-1 kinase activity and on MO7e cell proliferation. The ability of IP-10 and MIP-1 alpha to antagonize the synergistic action of GM-CSF and SLF appears to involve inactivation of Raf-1 and the down-regulation of protein synthesis. Our findings suggest that both MIP-1 alpha and IP-10 mediate their suppressive effects in MO7e cells by stimulating increases in cellular cAMP levels and activating protein kinase A, a mechanism we believe to be unique to these chemokines and not one applied to all growth suppressive members of the chemokine superfamily (for example, interleukin 8 and platelet factor 4).
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PMID:Interferon-inducible protein 10 and macrophage inflammatory protein-1 alpha inhibit growth factor stimulation of Raf-1 kinase activity and protein synthesis in a human growth factor-dependent hematopoietic cell line. 1660 26

We have further characterized the biological activities, mechanism of action, and target cell populations of recombinant human and murine thrombopoietin (rhTPO and rmTPO) in in vitro human and murine model systems. Alone, hTPO or mTPO stimulated the maturation of immature murine megakaryoblasts as measured in a single cell assay. The combination of hTPO or mTPO and interleukin-6 (IL-6) resulted in a further increase in megakaryocyte differentiation in this system. Murine TPO stimulated mouse megakaryocyte progenitor development. Human megakaryocyte progenitor development was potentiated by hTPO alone and further augmented in the presence of the early-acting cytokines (IL-3) or kit ligand/stem cell factor (KL/SCF). To further define the mechanism of action of TPO, neutralization studies were performed with antisera to IL-3, granulocyte-macrophage colony-stimulating factor (GM-CSF), IL-1 beta, and IL-11. No diminution in TPO activity was observed in the presence of these antisera. Moreover, because adhesive interactions are known to modulate hematopoiesis, we studied whether hTPO might alter such interactions between human bone marrow (BM) megakaryocytes and human BM stromal fibroblasts. No changes were observed in either megakaryocyte expression of the surface molecules lymphocyte function-associated antigen-1, very late activation antigen-4, or intercellular adhesion molecule-1 or the adhesion of megakaryocytes to stromal fibroblasts after treatment with the growth factor. Furthermore, no induction of secretion of the cytokines IL-1 alpha, IL-1 beta, GM-CSF, IL-6, granulocyte-CSF, tumor necrosis factor-alpha, transforming growth factor-beta 1, or transforming growth factor-beta 2 by primary human BM megakaryocytes was noted after treatment of the cells with hTPO. To address whether TPO affects very primitive hematopoietic progenitors, we studied the residual cells from the BMs of mice treated with high doses of 5-fluorouracil. Although no effect of mTPO alone was noted on the viability or replication of such primitive murine progenitor populations, the triple combination of IL-3 + KL/SCF + TPO stimulated growth of megakaryocyte progenitors. These results indicate that TPO is a highly lineage-specific growth factor whose primary biological effects are likely to be direct modulation of the growth and maturation of committed megakaryocyte precursors and immature megakaryoblasts.
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PMID:Modulation of megakaryocytopoiesis by thrombopoietin: the c-Mpl ligand. 763 39

Basic fibroblast growth factor or fibroblast growth factor-2 (FGF) has been shown to affect myeloid cell proliferation and hypothesized to stimulate primitive hematopoietic cells. We sought to evaluate the effect of FGF on hematopoietic stem cells and to determine if FGF mediated its effects on progenitor cells directly or through the induction of other cytokines. To address the direct effects of FGF, we investigated whether FGF induced production of interleukin-1 beta (IL-1 beta), tumor necrosis factor alpha, IL-6, granulocyte colony-stimulating factor, or granulocyte-macrophage colony-stimulating factor by two types of accessory cells, bone marrow (BM) fibroblasts and macrophages. We further evaluated whether antibodies to FGF-induced cytokines affected colony formation. To determine if FGF was capable of stimulating multipotent progenitors, we assessed the output of different colony types after stimulation of BM mononuclear cells (BMMC) or CD34+ BMMC and compared the effects of FGF with the stem cell active cytokine, kit ligand (KL). In addition, a subset of CD34+ BMMC with characteristics of hematopoietic stem cells was isolated by functional selection and their response to FGF was evaluated using proliferation, colony-forming, and single-cell polymerase chain reaction (PCR) assays. We determined that FGF had a stimulatory effect on the production of a single cytokine, IL-6, but that the effects of FGF on colony formation were not attributable to that induction. FGF was more restricted in its in vitro effects on BM progenitors than KL was, having no effect on erythroid colony formation. FGF did not stimulate stem cells and FGF receptors were not detected on stem cells as evaluated by single-cell reverse transcription PCR. In contrast, FGF receptor gene expression was detected in myeloid progenitor populations. These data support a directly mediated effect for FGF that appears to be restricted to lineage-committed myeloid progenitor cells. FGF does not appear to modulate the human hematopoietic stem cell.
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PMID:Basic fibroblast growth factor mediates its effects on committed myeloid progenitors by direct action and has no effect on hematopoietic stem cells. 766 60

To characterize the growth of cord blood progenitor cells, single nonadherent, low-density, T-lymphocyte-depleted CD34 cells were sorted by flow cytometer with an autoclone device into single wells containing culture medium and cytokines. These cells were evaluated for proliferation and for replating ability of their progeny. This latter effect is used as a measure of self-renewal capacity. Colony formation was assessed in 1 degree wells containing various cytokines, alone and in combination, and single colonies deriving after 21 days in semisolid medium were replated into 2 degree wells in the presence of the combination of purified preparations of recombinant human steel factor (SF, a c-kit ligand), granulocyte-macrophage colony-stimulating factor (GM-CSF), granulocyte colony-stimulating factor (G-CSF), interleukin-3 (IL-3), and erythropoietin (Epo). Replating of single colonies was performed also for 3 degrees, 4 degrees, and 5 degrees cultures. In the presence of serum, colony formation was observed in > 66% of the wells stimulated with the combination of Epo, SF, GM-CSF, G-CSF, and IL-3, and more than 39% of the colonies formed in these 1 degree wells were very large in size (> 2.5 mm in diameter, dense in the center, and containing > 10(4) cells/colony). The replating efficiency of these large colonies was up to 93% with generation of subsequent colonies of very large size. Replating could be shown for up to five generations. The cells in these colonies were large, nonspecific esterase positive, and contained large amounts of cytoplasm with one or more nuclei containing several nucleoli per nucleus. Smaller colonies (1 to 2.5 mm in diameter and dense in the center) containing similar cells and making up an additional 14% of the colonies formed in 1 degree wells also showed extensive replating capacity, including generation of larger colonies. These colony-forming cells are likely similar to the murine macrophage high-proliferative potential colony-forming cells. The cells giving rise to these colonies are present in about eightfold higher frequency in cord blood than in adult bone marrow. These cells may at least in part be associated with the successful hematopoietic repopulating capacity of umbilical cord blood cells.
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PMID:Enrichment, characterization, and responsiveness of single primitive CD34 human umbilical cord blood hematopoietic progenitors with high proliferative and replating potential. 767 69

Survival after irradiation with LD100/30 (radiation dose lethal to 100% of mice in 30 days) is based on recovery of impaired hematopoietic function. Our previous studies using antibodies to interleukin-1 receptor (IL-1R), tumor necrosis factor (TNF), and IL-6 demonstrated that endogenous production of these three cytokines is required for untreated mice as well as mice protected with lipopolysaccharide (LPS), IL-1, or TNF to survive lethal irradiation. In this report we show that anti-c-kit ligand/steel factor (SIF) antibody similarly abrogates LPS- and IL-1-induced radioprotection. Furthermore, administration of this antibody to unmanipulated mice increased LD50/30 radiation lethality from 50% to 100%. Such an effect was not obtained using anti-IL-3, anti-IL-4, or anti-granulocyte-macrophage colony-stimulating factor antibody. Thus, like IL-1, TNF, and IL-6, SIF is required for survival from lethal irradiation.
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PMID:Inhibition of c-kit ligand/steel factor by antibodies reduces survival of lethally irradiated mice. 767 9

The replating capability of human umbilical cord blood (CB) multipotential (CFU-GEMM) progenitors was assessed in vitro as an estimate of self-renewal using erythropoietin (Epo), steel factor (SLF), and either fetal bovine serum (FBS) or CB plasma. This study found a much higher replating efficiency for CB CFU-GEMM than previously reported, in terms of the percentage of colonies that could be replated, the number of secondary colonies per replated primary colony, and the size of secondary colonies. Moreover, the majority of secondary colonies were CFU-GEMM-derived. Although the percentages of bone marrow CFU-GEMM that replate was similar to that for CB CFU-GEMM and the sizes of secondary bone marrow and CB CFU-GEMM were also similar, replated CB CFU-GEMM gave rise to far greater numbers of secondary colonies. No tertiary colonies were observed when secondary CFU-GEMM were replated. Detection of extensive secondary replating potential was enhanced by the addition of CB plasma to the cultures. This activity was not found in either adult blood (PB) plasma, umbilical cord vein endothelial cell-conditioned medium (ECCM), FBS plus ECCM, or FBS plus the combination of interleukin-1 (IL-1), IL-3, IL-6, IL-11, granulocyte colony-stimulating factor, and granulocyte-macrophage colony-stimulating factor. Whether the CB plasma-enhancing activity for CFU-GEMM replating capacity is attributable to a novel factor or factors, or represents effects of other known cytokines, alone or in combination, remains to be determined. Of particular relevance, these studies suggest that human CFU-GEMM have some degree of stemness and perhaps should be classified as a subset of stem cells.
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PMID:Human multipotential progenitor cells (CFU-GEMM) have extensive replating capacity for secondary CFU-GEMM: an effect enhanced by cord blood plasma. 767 10

We have investigated the stimulative effects of mast cell growth factor (MGF) in primary acute myeloid leukemia (AML) in vitro. MGF stimulated DNA synthesis of purified leukemic blasts in eight out of 10 cases and colony formation in four cases in serum-free (SF) culture. MGF synergized with interleukin-3 (IL-3; four out of 10 cases), granulocyte-macrophage colony-stimulating factor (GM-CSF; three out of 10 cases), granulocyte colony-stimulating factor (G-CSF; six out of 10 cases), macrophage colony-stimulating factor (M-CSF; one out of 10 cases) and erythropoietin (EPO; one out of 10 cases) when added to culture in combination. Synergistic effects of MGF in combination with other CSFs were also seen in the colony assay. Antibodies against GM-CSF, M-CSF, G-CSF, and IL-6 did not inhibit the MGF response, suggesting that the stimulative effect of MGF was not mediated through autocrine release of those cytokines. Cell recovery data in liquid cultures that contained MGF, IL-3, or MGF + IL-3, indicated that both MGF and IL-3 augmented the maintenance of clonogenic cells as compared to nonsupplemented cultures, but the effect of the combination of IL-3 + MGF did not show synergy. In contrast, activation of DNA synthesis by MGF was abrogated in the presence of tumor necrosis factor (TNF; four out of 10 cases) and interleukin-4 (IL-4; two out of 10 cases). Fluorescence-activated cell sorting (FACS) analysis with anti c-kit antibodies revealed MGF receptor expression in eight out of nine cases, often in a subpopulation of the cells. Scatchard analysis of MGF receptors in two cases indicated the presence of 1460 and 41,500 (mean) binding sites, respectively, of high affinity (Kd 40-160 pmol/l). The MGF dose-response curve in the presence of IL-3 or GM-CSF resulted in a higher plateau of DNA synthesis, however no shift in the dose response was apparent. The respective reciprocal dose response relations to GM-CSF, IL-3, or G-CSF were similarly elevated when MGF was added. MGF did not alter IL-3 and GM-CSF receptor expression, nor did IL-3, GM-CSF, G-CSF, TNF, or IL-4 influence MGF binding to AML cells.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Effects of mast cell growth factor on acute myeloid leukemia cells in vitro: effects of combinations with other cytokines. 768 Apr 1

Cells of the murine interleukin-3 (IL-3) or granulocyte-macrophage colony-stimulating factor (GM-CSF) factor-dependent line, FDC-P1, express the tyrosine kinase receptor, c-kit. The ligand for c-kit, steel factor (SLF), encoded by the steel (Sl) locus, is produced as both membrane-bound and soluble forms by fibroblastoid cells. Fibroblasts derived from normal (+/+) WCB6F1 mice are known to produce both forms of SLF and were able to support FDC-P1 cells in a contact-dependent manner in the presence of neutralizing anti-GM-CSF antiserum. In contrast, Sl/Sld mutant fibroblasts, which produce only a soluble form of SLF, were incapable of supporting FDC-P1 cells in the presence of GM-CSF antiserum. These results suggested that FDC-P1 cells were being supported on fibroblast layers by membrane-bound SLF. Attempts to grow FDC-P1 cells in high levels of soluble recombinant SLF to mimic the SLF-dependent response seen in co-culture experiments showed that cells which had been previously grown in GM-CSF or IL-3 were minimally responsive to SLF at concentrations up to 100 ng/mL. Although these cultures were not supported by SLF alone, the cells showed synergistic proliferative responses to SLF combined with suboptimal levels of GM-CSF or IL-3. FDC-P1 cells could, however, be adapted to grow in SLF alone by gradual substitution of SLF for GM-CSF over a period of 3 weeks. These cells showed 5.6- to 8.4-fold and 2.5-fold higher levels of c-kit mRNA than cells grown in GM-CSF or IL-3, respectively. Downregulation of surface c-kit protein was also seen in FDC-P1 cells grown in GM-CSF or IL-3 compared with cells grown in SLF. Although FDC-P1 cells propagated in SLF were more responsive to SLF, they were still able to proliferate as well in GM-CSF and IL-3 as the cells originally grown in the latter factors. Thus, functional downregulation of c-kit by GM-CSF and IL-3 was unidirectional.
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PMID:Responses of the murine myeloid cell line FDC-P1 to soluble and membrane-bound forms of steel factor (SLF). 768


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