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Query: UMLS:C0023418 (leukemia)
 93,477 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Myeloid leukemia development requires the acquisition by a cell of two abnormalities: an abnormal capacity for self-replication; and a capacity for autocrine stimulation, usually involving the known growth factors for granulocyte-macrophage cells. Curiously, in human leukemia, this does not usually result in autonomous growth when assessed in clonal in vitro cultures. Depending on gene programming, in particular in human or murine myeloid leukemias, the hemopoietic growth factors can also suppress the leukemic population by inhibiting the capacity of the leukemic stem cells for self-generation. The regulator showing the highest suppressive activity varies from leukemia to leukemia, with G-CSF. GM-CSF, IL-6, or leukemia-inhibitory factor (LIF) all having high activity on appropriate target cells. Combinations of these regulators are more effective than single agents alone. Analyses of human HL60, U937 and murine M1 leukemic models indicate that the development of morphological maturation in the leukemic cells is not a necessary feature of stem-cell suppression. LIF has an anomalous action on stem-cell self-generation, being highly effective in the suppression of certain myeloid leukemic cell lines, but being necessary to maintain self-generation in normal embryonic cells. This suggests the existence of a common control medium governing self-generation decisions in cells of different lineages, but that the outcome of the decision is determined by the differentiation program operating in different cells. The colony-stimulating factors are being used in combination with chemotherapy in the treatment of patients with acute myeloid leukemia, but the above principles require caution in certain situations.
Leukemia 1992
PMID:Role of hemopoietic growth factors in the development and suppression of myeloid leukemia. 160 21

Thuja polysaccharide g fraction (TPSg) was shown to be an inducer of the CD4+ fraction of the human peripheral blood T-cell subset (1,2). Furthermore, it could be demonstrated that TPSg is a potent inhibitor of the expression of HIV-1-specific antigens and of the HIV-1-specific reverse transcriptase (3). This report deals with the cytokine pattern induced by TPSg in human peripheral blood lymphocyte (PBL) and purified monocyte/macrophage cultures. In addition, a further characterization of the CD4+ T-cell fraction stimulated by TPSg was performed by FACS analysis. TPSg is induces IL-1 beta, IL-2, IL-3, IL-6, gamma-IFN, G-CSF, GM-CSF, and TNF-beta production in PBL cultures; and IL-1 beta and IL-6 in monocyte/macrophage cultures. Enzyme-linked immunosorbent assays (ELISAs) demonstrated that no IL-4 was produced by PBL cultures under TPSg influence.
Leukemia 1992
PMID:Mitogenic activity of high molecular polysaccharide fractions isolated from the cuppressaceae Thuja occidentalis L. enhanced cytokine-production by thyapolysaccharide, g-fraction (TPSg). 160 22

We examined the stimulatory effects of recombinant human granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin 6 (IL)-6 on the in vitro proliferation of leukemic blast cells from patients with acute leukemia. Bone marrow or peripheral blood leukemic blast cells were obtained from 21 patients, including 14 cases of acute myeloblastic leukemia (AML), four cases of acute lymphoblastic leukemia (ALL), two cases of acute undifferentiated leukemia, and one case of acute mixed-lineage leukemia. The proliferation of leukemic blast cells was evaluated by measuring the incorporation of 3H-thymidine into cells incubated with various concentrations of cytokines for 3 days. GM-CSF stimulated the DNA synthesis (with greater than 2.0 stimulation index) of blast cells in 9 of 14 (64%) AML cases, two cases of acute undifferentiated leukemia and one case of acute mixed-lineage leukemia. Only two cases of AML blasts responded to IL-6 to grow in the short-term suspension cultures. GM-CSF and IL-6 did not display a synergistic effect on the growth of leukemic cells. Moreover, GM-CSF and IL-6 did not stimulate the proliferation of ALL blast cells. Binding study also revealed the specific binding of GM-CSF on the blast cells of acute undifferentiated leukemia and acute mixed-lineage leukemia. Our results indicated that leukemic blast cells of acute undifferentiated leukemia and acute mixed-lineage leukemia possessed functional GM-CSF receptors.
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PMID:Effects of granulocyte-macrophage colony-stimulating factor and interleukin 6 on the growth of leukemic blasts in suspension culture. 161 67

4-Hydroperoxycyclophosphamide (4-HC) is widely used as an ex vivo bone marrow purging agent for acute myeloid leukemia (AML) blasts. We have determined the effect of a combined treatment with interleukin 3 (IL-3) plus IL-6 on 4-HC cytotoxicity against normal (CFU-GEMM) versus AML (L-CFU) bone marrow progenitor cells. Following an 18 h exposure to IL-3 plus IL-6, treatment with 4-HC in conjunction with IL-3 and IL-6 for one hour resulted in a significantly greater inhibition of L-CFU versus CFU-GEMM colony growth. In addition, treatment with IL-3 plus IL-6 reduced the inhibitory effects of higher concentrations of 4-HC on CFU-GEMM but not L-CFU growth. IL-3 and IL-6 did not protect the self-renewing, clonogenic, AML blast progenitor cells from the cytotoxic effects of 4-HC. While the total intracellular glutathione (GSH) levels were not significantly different between untreated normal bone marrow mononuclear cells (NBMMC) and AML blasts, greater intracellular GSH-S transferase activity was observed in the NBMMC. 4-HC produced a marked reduction in GSH levels in NBMMC as well as AML blasts. But treatment with IL-3 plus IL-6 in conjunction with 4-HC resulted in significantly higher GSH levels in NBMMC. These differences in intracellular GSH levels and GST activity may offer an explanation for the differential protective effects of IL-3 plus IL-6 treatment against the cytotoxic effects of 4-HC on CFU-GEMM colony growth.
Leukemia 1992 Aug
PMID:Effect of combined treatment with interleukin-3 and interleukin-6 on 4-hydroperoxycyclophosphamide-mediated reduction of glutathione levels and cytotoxicity in normal and leukemic bone marrow progenitor cells. 164 Jul 34

NFS60, a murine leukemia cell line, responds to both interleukin 3 and 6 by proliferating, apparently by different signal transduction pathways. Although stimulation by both cytokines increases the uptake of 3H-arachidonic acid, the response to IL-6 was much faster. Furthermore, the effect of various arachidonic acid metabolites on the response to cytokine was different. PGE2 inhibited IL-6-induced proliferation and potentiated the response to IL-3. Additionally the G proteins which coupled the IL-3 and IL-6 receptor to the proliferative response are probably different, based on the ability of cholera toxin to inhibit the IL-3 but not the IL-6 response. These data are evidence of two pathways of signal transduction.
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PMID:Two pathways of signal transduction are activated in the same cell by different cytokines. 166 44

The binding of haemopoietic growth factors and cytokines to specific receptors triggers a cascade of intracellular events which results in cell proliferation and differentiation. The knowledge of ligand-receptor-signal pathways is not only important in understanding the pathophysiology of malignant disease but also essential for devising future therapeutic strategies. The advent of recombinant technology has made it possible to test the efficacy of selective differentiation therapy, and haemopoietic growth factors are undergoing clinical trials for a number of indications. In addition, increasingly the receptors for haemopoietic growth factors and cytokines have come under scientific scrutiny. Recently receptors for IL-2 alpha, IL-2 beta, IL-3, IL-4, IL-5, IL-6, IL-7, erythropoietin, G-CSF and GM-CSF have been isolated and cloned. It has become apparent that they have structural homology that is shared by receptors for growth hormone and prolactin, and this receptor group makes up the new cytokine receptor superfamily. The finding of sequence homology within these receptors suggests their evolutionary relationship. These receptors are transmembrane proteins 257-856 amino acids and their extracellular ligand-binding domain contains four conserved cysteine residues and a Trp-Ser-X-Trp-Ser motif. The secondary structure of the extracellular domain is made up of alpha-helices. High and low affinity binding forms exist for all these receptors. Binding affinity may depend on the formation of receptor heterodimers or multimers, association with other membrane proteins or differential glycosylation. Soluble receptor forms have been described for IL-2 alpha, IL-4, IL-5, IL-6 and IL-7. It is not known whether they are actively secreted or represent the degradation products of cell turnover. Their function may be to mop up excess cytokines and thereby confine the cytokine response. There is no sequence homology of the intracytoplasmic domains although several are rich in proline and serine residues, which may be important in mechanisms of signal transduction. No receptor in this superfamily functions as a receptor tyrosine kinase or has intrinsic protein tyrosine kinase activity. Detailed study of individual receptors holds clues to the regulation of receptor expression, ligand-receptor interactions and mechanisms involved in signal transduction. Such knowledge might explain the pleotropic effects cytokines may have on different cell types and their overlap in biological functions. Elevated levels of soluble IL-2 alpha receptor (Tac) are detected in hairy cell leukaemia, lymphomas and adult T-cell leukaemia (TL), and levels reflect tumour burden.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:The cytokine receptor superfamily. 166 10

For granulocytic-macrophage progenitor populations and their progeny, five glycoproteins have been identified: GM-CSF, G-CSF, multi-CSF, M-CSF and IL-6 that can regulate their proliferative activity, maturation and functional activities. The same glycoproteins also have a capacity to induce irreversible differentiation commitment in normal bipotential granulocyte-macrophage progenitors and in some myeloid leukaemic cell lines, which suggests that common cellular processes exist in both situations. The leukaemia inhibitory factor (LIF) is a glycoprotein, with intriguing properties, which can either induce differentiation in some myeloid leukaemic cell lines or prevent differentiation in normal totipotential embryonic stem cells. The data from the LIF studies suggest a genetic mechanism controlling self-generation that is relatively simple and may be common to all cells. However, the actual cellular response observed appears to depend on the nature of the responding cell.
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PMID:The induction and inhibition of differentiation in normal and leukaemic cells. 169 Sep 2

We have examined the in vitro effects of recombinant human (rh) interleukin-1 (IL-1) on the growth of purified megakaryoblasts obtained from patients with acute megakaryoblastic leukemia. We demonstrate that both IL-1 alpha and IL-1 beta treatment of these cells led to stimulation of DNA synthesis (as shown by increase of 3H-thymidine incorporation up to 35-fold) and also resulted in colony formation of leukemic megakaryoblasts. However, the stimulatory effect of IL-1 was dependent on endogenous production of IL-6, because addition of neutralizing monoclonal antibody (MoAb) to IL-6 abrogated the stimulatory activity of IL-1. In contrast, neutralizing MoAbs to granulocyte (G)-colony stimulating factor (CSF), granulocyte-macrophage (GM)-CSF, and macrophage (M)-CSF failed to counteract the growth-enhancing effects of IL-1. Leukemic megakaryoblasts accumulated IL-6 mRNA and released IL-6 protein into their culture supernatant when exposed to rh IL-1 but failed to disclose transcripts for G-, GM-, and M-CSF under these conditions. Analysis of IL-6 receptor (IL-6R) transcript levels demonstrated that megakaryoblasts constitutively expressed IL-6R mRNA and that these transcripts are down-regulated to undetectable levels upon exposure to IL-1 and IL-6. Increase of 3H-thymidine incorporation by megakaryoblasts could be duplicated by exogenous IL-6 that could be blocked by neutralizing MoAb to IL-6. In conclusion, our results suggest that leukemic megakaryoblasts could produce and secrete IL-6, and express IL-6R, and that the growth-enhancing effect of IL-1 on these cells is indirect, via production of IL-6 by leukemic cells.
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PMID:Interleukin-6 (IL-6) is an intermediate in IL-1-induced proliferation of leukemic human megakaryoblasts. 170 Jul 30

Mice infected with LP-BM5 murine leukemia virus (MuLV) develop a syndrome denoted as murine AIDS. Macrophages harvested from the peritoneal cavities of these mice at 4 or 9 wk postinoculation with LP-BM5 MuLV were analyzed by Northern hybridization for the presence of the defective LP-BM5 virus and their ability to synthesize various cytokines upon induction with Newcastle disease virus (NDV) or (LPS). Neither IFN-alpha or IFN-beta was found to be constitutively expressed in LP-BM5-infected macrophages and in NDV induction studies, and the levels of biologically active IFN-alpha and its mRNA were found to be lower in LP-BM5 MuLV-infected macrophages than in the macrophages from uninfected controls. Similarly, after NDV or LPS induction, the levels of TNF mRNA and TNF protein were significantly lower in LP-BM5-infected macrophages than in macrophages from uninfected mice. The LP-BM5 MuLV-infected macrophages constitutively expressed low levels of IL-1 beta, and when induced with LPS, the relative levels of IL-1 beta were significantly higher in infected than in uninfected macrophages. Although no constitutive expression of IL-6 was detected, the levels of IL-6 mRNA induced with NDV were higher in LP-BM5 MuLV-infected macrophages than in controls. Thus, we found alterations in the expression of selected cytokines in macrophages from mice inoculated with LP-BM5 MuLV rather than a general deregulation of all cytokine expression. These results show that macrophages infected with the defective LP-BM5 virus respond differently to NDV- or LPS-stimulation and suggest that aberrant expression of certain cytokine genes may play a role in the immunopathologic condition in mice with murine AIDS.
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PMID:Aberrant expression of cytokine genes in peritoneal macrophages from mice infected with LP-BM5 MuLV, a murine model of AIDS. 170 89

A syndrome characterized by severe immunodeficiency and lymphoproliferation develops in susceptible strains of mice infected with a mixture of murine leukemia viruses (MuLVs) designated LP-BM5 MuLV. The etiologic agent in this mixture has been shown to be a replication-defective virus (BM5d) with a 4.8-kb genome that required replication-competent helper viruses, primarily ecotropic (BM5e), for cell-to-cell spread in the host. In the present study, we studied the expression of BM5d and BM5e in tissues of infected mice at various times after inoculation in relation to the expression of cytokine genes that may contribute to the pathogenesis of this disorder. Northern (RNA) analysis of total RNA showed that BM5d was expressed at significant levels in lymphoid tissues within 1 week of infection and that the levels of expression increased with time after inoculation. By 16 weeks postinfection, BM5d was expressed in all tissues examined. Expression of BM5e was relatively more restricted to lymphoid tissues and was detected at lower levels than expression of BM5d at early times after infection, but this virus was expressed in all tissues by 16 weeks. Infection with the virus mixture was associated with constitutive expression of tumor necrosis factor in all tissues examined and of interleukin-1 (IL-1) in lymphoid tissues within 1 week of infection, and at later times with widespread expression of these cytokines and gamma interferon. Also, the levels of interferon regulatory factor 1 mRNA were significantly increased in all infected tissues during the infection. In contrast, expression of IL-3, IL-4, IL-5, and IL-6 was not detectable by Northern analysis of the respective mRNAs in any infected tissue at early or late times postinfection.
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PMID:Expression of defective virus and cytokine genes in murine AIDS. 170 43


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