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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 role of CD11/CD18 leukocyte adhesion molecules and their ligands in mediating non-major histocompatibility complex (MHC) restricted lymphocyte cytotoxicity is controversial. In order to examine the role of target cell intercellular adhesion molecule-1 (ICAM-1; CD54), a ligand of lymphocyte function-associated antigen (LFA-1) (CD11a/CD18), we exposed the human leukemia cell line, HL-60, to a variety of agents implicated in modulating ICAM-1 expression and/or sensitivity to lymphocyte cytolysis. Exposure of HL-60 cells to retinoic acid (RA), interferon (IFN)-alpha, IFN-beta, and IFN-gamma induced protection from lymphokine-activated killer (LAK) cytolysis. Only RA and IFN-gamma induced ICAM-1 expression. Tumor necrosis factor and vitamin D3, which also induced ICAM-1 expression, increased HL-60 sensitivity to LAK lysis. Granulocyte-macrophage colony-stimulating factor also increased sensitivity to LAK lysis; ICAM-1 was not induced. The state of cellular differentiation and expression of class I and II MHC antigens also did not correlate with sensitivity to LAK cytolysis. Exposure of untreated HL-60 cells and HL-60 cells expressing ICAM-1 to monoclonal antibody (mAb) versus ICAM-1 did not modulate LAK sensitivity. Exposure of LAK cells to mAb versus LFA-1 partially inhibited cytolysis; mAb versus CD18 inhibited cytolysis more completely. HL-60 cells were resistant to natural killer lysis; exposure to the various experimental agents did not alter sensitivity. We conclude that leukemic cell sensitivity to LAK cytolysis can be modulated by a variety of agents. Although our results suggest a role for leukocyte CD11/CD18 adhesion molecules in LAK cytolysis, the poor correlation between ICAM-1 expression and sensitivity to LAK lysis suggest that interactions other than LFA-1/ICAM-1 conjugation may be more central to the processes involved.
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PMID:Modulation of leukemic cell sensitivity to lymphokine-activated killer cytolysis: role of intercellular adhesion molecule-1. 136 53

The kit ligand (KL), also termed stem cell factor (SCF), is a recently discovered hematopoietic growth factor that augments response of early progenitor cells to other growth factors and supports proliferation of continuous mast cell lines. Histological studies suggest that the receptor for SCF/KL, the c-kit proto-oncogene product, is present in bone marrow megakaryocytes. We studied the effects of SCF/KL on immortalized human megakaryocytic cell lines (CMK, CMK6, and CMK11-5) and on isolated human marrow megakaryocytes. Human SCF/KL alone or in combination with the hematopoietic growth factors, interleukin-3 (IL-3), granulocyte-macrophage colony-stimulating factor (GM-CSF), and IL-6, stimulated proliferation of these megakaryocytic cell lines. SCF/KL treatment did not alter expression of gpIb, gpIIb/IIIa, LFA-1, ICAM-1, or GMP-140 in CMK cells. No effect on ploidy was observed. Furthermore, human SCF/KL induced expression of IL-1 alpha, IL-1 beta, IL-2, and IL-6 in CMK cells. In a fibrin clot system, SCF/KL modestly potentiated megakaryocyte colony formation when added alone to cultures containing CD34+, DR+ bone marrow cells. Addition of SCF/KL with IL-3 or GM-CSF to these cultures resulted in a more marked marrow megakaryocytic cells. SCF/KL may directly affect megakaryocytopoiesis, as well as secondarily modulate hematopoiesis through induction of cytokines in target cells.
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PMID:Effects of the stem cell factor, c-kit ligand, on human megakaryocytic cells. 137 Mar 86

The membrane molecule CD4 (L3T4) is thought to facilitate activation of Class II H-2-restricted T cells by binding to Ia determinants on antigen-presenting cells. Recent reports suggest that CD4 can also contribute to antigen-independent activation by anti-T cell receptor (TCR) antibodies. An assay which measures the secretion of two lymphokines, granulocyte-macrophage colony-stimulating factor and interleukin 3 (IL-3), by single T cells activated with an anti-TCR antibody, F23.1, was used to analyze the effects of anti-CD4 antibodies on antigen-independent T cell activation. Single cells of a CD4+F23.1+ clone were micromanipulated into wells to which F23.1 had been immobilized, and their lymphokine secretion was measured 24 hr later. The frequency of lymphokine-secreting cells was consistently reduced up to 10-fold in the presence of soluble anti-CD4 antibody (GK1.5) but only up to 2.5-fold by an antibody to the cell adhesion molecule, LFA-1. In both bulk and single-cell cultures, responses to suboptimal concentrations of F23.1 were more susceptible to inhibition by GK1.5 than responses to optimal F23.1. The failure of GK1.5 to inhibit IL-2-stimulated lymphokine synthesis in bulk cultures suggested that CD4 ligation did not deliver a negative signal to the clone. By contrast, when either anti-CD4 or anti-LFA-1 was immobilized on the same surface as F23.1, the frequency of lymphokine-secreting cells could be increased up to 10-fold. It is concluded that anti-CD4 antibodies can act directly on the responding T cell to affect TCR-dependent activation, in the absence of interaction with antigen-presenting cells or any other cell type.
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PMID:The role of CD4 in antigen-independent activation of isolated single T lymphocytes. 290 16

The CD11b (Mol) molecule is a member of a family of surface glycoproteins that are essential for adhesion-dependent granulocyte functions. Brief exposure of granulocytes to human granulocyte-macrophage colony-stimulating factor (GM-CSF) in vitro increases the surface expression of CD11b and increases granulocyte adhesiveness. To assess the possible in vivo significance of these observations we studied the effect of GM-CSF on CD11b, CD11a (LFA-1), and CD11c (gp 150, 95) expression on granulocytes from nine adult patients with sarcoma who were receiving GM-CSF as part of a phase I trial. GM-CSF was administered as a continuous infusion at a dose of 32 or 64 micrograms/kg/d. Granulocyte CD11b, CD11a, and CD11c expression was determined by indirect immunofluorescence staining of whole blood, thereby minimizing in vitro manipulation. A transient leukopenia developed within 15 minutes of initiation of GM-CSF treatment that was associated with a marked increase in the surface antigen density of CD11b. A mean 1.7-fold increase (P = .001) in the percentage of CD11b-positive granulocytes and a mean 2.1-fold increase (P = .002) in CD11b surface antigen density was noted after 12 hours of treatment. No change in CD11a or CD11c expression was observed over the first 12 hours. The level of CD11b expression was followed in six patients for up to 5 days of treatment with GM-CSF. Compared with the 12-hour value, three of six patients showed a subsequent decrease in CD11b expression, two remained constant, and one showed a continued increase in CD11b surface density. Fluorescence-activated cell sorting of granulocytes into high- and low-density CD11b-positive groups revealed a preponderance of immature myeloid forms in the low-density CD11b fraction, which suggests that the late decrease in CD11b expression in some patients may be related to a greater proportion of circulating immature myeloid forms in the peripheral blood. This study suggests that GM-CSF administered as a continuous infusion rapidly upregulates the expression of granulocyte CD11b in vivo. The influence of this phenomenon on in vivo granulocyte aggregation may be clinically relevant with regard to the toxicity of GM-CSF and deserves further investigation.
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PMID:Granulocyte-macrophage colony-stimulating factor induces the expression of the CD11b surface adhesion molecule on human granulocytes in vivo. 304 45

We assessed the expression of the adhesion molecules leukocyte function antigen-1 (LFA-1, CD11a), intercellular adhesion molecule-1 (ICAM-1, CD54), homing-associated cell adhesion molecule (H-CAM, CD44), and c-kit (stem cell factor receptor) on the CD34+ progenitor population from the leukapheresis products of 23 patients (LP CD34+). For blood stem cell collection granulocyte colony-stimulating factor (G-CSF) or interleukin-3/granulocyte-macrophage colony-stimulating factor (IL-3/GM-CSF) was administered after cytotoxic chemotherapy. Furthermore, bone marrow- and blood-derived CD34+ progenitor cells from 6 normal volunteers (BM and PB CD34+) were analyzed. LFA-1 expression was higher on PB CD34+ (88.2 +/- 2.5%, mean +/- SEM) than on BM CD34+ (75.3 +/- 4.3%). Following cytokine administration, LFA-1 was expressed on only 59.7 +/- 3.7% of LP CD34+ at a low fluorescence intensity, suggesting that down-regulation of LFA-1 may facilitate the egress of cells from the bone marrow and prolong their circulation. In contrast, ICAM-1 was weakly positive on CD34+ cells from all sources. CD44 was expressed on the vast majority of CD34+ cells (> 95%) in all samples studied. The highest proportion of CD34+ cells costaining for c-kit was found in normal bone marrow (32.2 +/- 3.3%). In normal peripheral blood and after cytokine mobilization, fewer of the CD34+ cells weakly expressed c-kit (< 15%). The low percentage and level of c-kit expression may indicate that the majority of cytokine-mobilized CD34+ cells are lineage-committed progenitor cells, as reflected by the coexpression pattern for CD38, HLA-DR, and CD33.
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PMID:Expression of adhesion molecules and c-kit on CD34+ hematopoietic progenitor cells: comparison of cytokine-mobilized blood stem cells with normal bone marrow and peripheral blood. 752 8

In the present study, the biological properties of cord blood cells were investigated. Cord blood mononuclear cells and T cells responded normally to activation by alloantigens in primary mixed leukocyte reactions (MLRs), indicating that cord blood T cells can be normally activated via their TcR and have normal proliferative capacities. In addition, they expressed normal levels of accessory molecules such as CD28 and LFA-1, which contribute to amplify their responses. In contrast, cord blood mononuclear cells, but not cord blood monocytes, had a reduced capacity to stimulate allogeneic cells in primary MLRs. In addition, cord blood monocytes express lower levels of HLA-DR and ICAM-1 compared to adult peripheral blood monocytes. Cord blood mononuclear cells were also impaired in their capacity to generate allogeneic cytotoxic activity in primary mixed leukocyte cultures (MLCs). In contrast, cord blood B cells were similar to adult B cells in their capacity to switch to immunoglobulin E producing cells when incubated with interleukin-4 (IL-4) and anti-CD40 monoclonal antibody. We also demonstrated that IL-2, IL-6, and tumor necrosis factor-alpha (TNF-alpha) production by activated cord blood mononuclear cells was comparable to that observed with peripheral blood mononuclear cells isolated from normal adult donors. In contrast, interferon-gamma (IFN-gamma) was significantly decreased, whereas IL-4 and IL-5 were absent. Granulocyte-macrophage colony-stimulating factor (GM-CSF) levels were in general higher in the supernatants of cord blood cells. Thus, cord blood immune responses differ from those of peripheral blood at several levels. Whether these differences account for a reduced capacity of transplanted cord blood cells to modulate graft vs. host disease remains to be determined.
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PMID:Immune responses by cord blood cells. 774 23

Interleukin-13 (IL-13) is a pleiotropic cytokine that inhibits the production of inflammatory cytokines of monocytes. We investigated the effects of IL-13 on the clonal growth of human hematopoietic progenitors. IL-13 alone did not support any colony formation. IL-13 markedly suppressed macrophage colonies that were formed in the presence of IL-3 and erythropoietin, granulocyte-macrophage colony-stimulating factor, or macrophage colony-stimulating factor. Macrophage colony cells showed dendritic cell-line morphology and cellular aggregates. IL-13 did not affect granulocyte colony and erythroid burst formation. Delayed addition of IL-13 and replating onto the culture dishes with IL-13 showed that macrophage colony formation was suppressed during days 8 and 14 of culture. These results indicate that IL-13 affects the growth of the late stage of committed macrophage progenitors. Single-cell culture of isolated CD34+CD33+ cells with IL-13 confirmed that macrophage colony formation was significantly suppressed. These results show that IL-13 directly suppresses the proliferation of differentiating macrophages. In addition, these suppressive effects of IL-13 were synergistic with IL-4. Furthermore, in the liquid culture of bone marrow cells in the presence of IL-13, the number of CD14 (monocyte-macrophage antigen)-positive cells decreased and CD18 (LFA-1 beta)-positive cells increased. It is concluded that IL-13 affects the growth of the late stage of macrophage precursors as well as mature monocytes. Induction of differentiation of human monocytes may be correlated with the suppression of their progenitors.
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PMID:Interleukin-13 selectively suppresses the growth of human macrophage progenitors at the late stage. 778 Jan 35

Dendritic cells (DC) isolated from the lymph nodes or spleens of mice and pulsed with contact sensitizers or protein antigens stimulate primary proliferative responses by syngeneic T cells and responses to alloantigens in the mixed leucocyte reaction (MLR). Using enriched human peripheral blood DC, we attempted to stimulate primary immune responses to contact sensitizers by autologous lymphocytes in vitro. No significant proliferation above background levels or CD69 expression (an early activation antigen on lymphocytes) was detected despite using a wide range of donors, chemicals, antigens and cell concentrations. Culture of DC for up to 5 days in vitro in the presence of phytohaemagglutinin (PHA)-conditioned culture supernatants, or recombinant granulocyte-macrophage colony-stimulating factor (GM-CSF) also failed to induce primary proliferative responses to contact sensitizers. Comparisons were made between blood and lymph node DC from mice to explore whether the lack of stimulation was the result of differences between mouse and human DC or between DC isolated from different tissues. DC from lymph nodes stimulated primary responses to contact sensitizers in both blood and lymph node lymphocytes whereas blood DC did not stimulate responses. Both lymph node and blood DC stimulated an allogeneic MLR, although blood DC were less efficient than those from lymph node. The data show that DC from different tissues exhibit variable functional activity. DC from blood and lymph nodes were examined to determine whether surface antigen expression is related to functional activity. Murine blood DC expressed similar levels of LFA-1, LECAM-1 and CD44 compared with lymph node DC but lower levels of MHC class II, B7 and ICAM-1. These results may therefore have important implications for antigen processing and presentation in cells from different tissue compartments.
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PMID:Differential function of dendritic cells isolated from blood and lymph nodes. 783 50

Eosinophils interact with extracellular matrix proteins and endothelial cells through adhesion proteins belonging to the beta 1 and beta 2 subfamilies of integrins. Extending previous observations, we found that tumour necrosis factor (TNF) and granulocyte-macrophage colony-stimulating factor stimulated generation of superoxide anion by eosinophils plated on fibronectin-coated surfaces. As studies with adherent neutrophils indicated that TNF might act as activating leucocyte integrins to deliver signals involved in activation of cell functions, we investigated the effects of monoclonal antibodies (mAb) directed against VLA-4 (CD49d/CD29), LFA-1 (CD11a/CD18), CR3 (CD11b/CD18) or the common beta 2 subunit (CD18) on generation of eosinophil toxic oxygen molecules and spreading. We show that cross-linking of members of both the beta 1 and the beta 2 integrin subfamilies triggers eosinophil respiratory burst and spreading. Evidence for the selectivity of anti-integrin mAb effects is derived from the findings that isotype-matched mAb of other specificities (anti-class I MHC Ag, anti-beta 2-microglobulin, anti-CD4) did not trigger eosinophil functions. The findings presented in this paper suggest that integrin-dependent, eosinophil adhesion in sites of allergic reaction may be accompanied by release of toxic oxygen molecules involved in tissue damage.
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PMID:Ligation of members of the beta 1 or the beta 2 subfamilies of integrins by antibodies triggers eosinophil respiratory burst and spreading. 790 78

CD11a, the alpha chain of LFA-1, which is a member of the LeuCAM family of integrins, has been implicated in the formation of HIV-induced syncytia and may contribute to the depletion of CD4-positive lymphocytes seen in patients with HIV infection. In this study, we examined the effects of HIV-1 infection on the expression of CD11a on cultured monocyte-derived macrophages (MDMs). Monocytes isolated from peripheral blood and maintained in suspension culture were infected in vitro with a monocytotropic variant of HIV-1 (Ba-L). Surface expression of CD11a, measured by indirect immunofluorescence and flow cytometry, was significantly higher on HIV-infected cells than on mock-infected cells from the same donor. Upregulation of CD11a expression was unaffected by the HIV reverse transcriptase inhibitor, zidovudine, indicating that it did not depend on reverse transcription. A step before reverse transcription, such as viral binding, appears sufficient to trigger an increase in CD11a expression. This hypothesis is supported by our findings of soluble recombinant CD4 inhibition of HIV-induced CD11a upregulation. It is possible that induction of a cytokine network by HIV underlies this effect, given our findings that exposure of uninfected MDMs to granulocyte-macrophage colony-stimulating factor (GM-CSF) specifically increased CD11a expression and that HIV-infected MDMs secreted more GM-CSF than mock-infected cells.
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PMID:Effects of HIV-1 on the surface expression of LFA-1 on cultured monocytes. 924 Nov 7


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