UNIPROT:P05231 - FACTA Search

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Query: UNIPROT:P05231 (interleukin-6)
23,907 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Recombinant human interleukin-6 (IL-6) has previously been shown to increase platelet counts in mice and primates. To elucidate the mechanisms underlying this phenomenon, serial analyses were performed on megakaryocytes obtained from rhesus monkeys treated for 8 days with 30 micrograms/kg/d of recombinant human IL-6. Platelet counts increased to a maximum of 7.8 x 10(5)/microL with biphasic peaks on days 7 and 12 without significant changes in platelet volumes. Large increases in DNA content were seen by two-color flow cytometry and digital image analysis. Ploidy distribution underwent a significant shift between study days 3 and 11 (P less than .0001) with large increases in the frequency of 64N and 128N megakaryocytes. The modal ploidy increased from the normal 16N to 64N. Megakaryocyte size, as measured by area, was increased 2- to 2.7-fold. On day 3, multiple megakaryocytes were seen in endomitosis, along with an abundance of young cells with wide, organelle-free peripheral zones. The giant megakaryocytes seen on days 5 to 7 exhibited marked membrane hyperplasia that occupied much of the cell. Emperipolesis occurred frequently, as did megakaryocyte cell death. No giant platelets were seen. We conclude that IL-6 significantly alters the process of megakaryocyte maturation and thrombocytopoiesis, and that these effects, at least in the doses of IL-6 administered, should not be equated with the physiologic mechanisms operative during accelerated platelet production.
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PMID:Effects of human interleukin-6 on megakaryocyte development and thrombocytopoiesis in primates. 188 16

We examined whether recombinant cytokines enhance the in vitro platelet production of interleukin-3 (IL-3)-induced human megakaryocytic colonies (Meg-colony). We classified Meg-colonies into four categories based on platelet production during in situ observation on day 14: type 0, absence of cytoplasmic processes in a colony; type 1, one to three processes in at least one megakaryocyte in a colony; type 2, four to eight processes; type 3, more than nine processes or division of cytoplasm. Type 3 colonies were considered to be platelet-producing. In control cultures, type 1 Meg-colonies were dominant, followed by type 2, type 3 and type 0. Of the cytokines added at the initiation of culture, interleukin-1 alpha (IL-1 alpha), interleukin-6 (IL-6), and granulocyte/macrophage colony stimulating factor (GM-CSF) significantly increased the number of colonies. Furthermore, these three cytokines significantly elevated the proportion of type 3 colonies. Interleukin-4 (IL-4), granulocyte-CSF, macrophage-CSF and erythropoietin did not affect the colony count or distribution of colony type. IL-1 alpha, IL-6 and GM-CSF also significantly elevated the proportion of type 3 colonies, even when added to the culture on days 8 or 11. These results indicate that IL-1 alpha, IL-6 and GM-CSF promote platelet production of in vitro Meg-colonies.
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PMID:Megakaryocyte potentiating activity of IL-1, IL-6 and GM-CSF as evaluated by their action on in vitro human megakaryocytic colonies. 191 39

The effect of interleukin-6 (IL-6) on cells of human megakaryocyte (MK) lineage from cord blood was explored. In semisolid colony assays containing human plasma, a greater number of both MK colonies and cells per colony was seen in the presence of IL-6 and IL-3 than in the presence of IL-3 alone. This stimulatory effect of IL-6, observed on both small and large MK colonies, was completely eliminated by the addition of anti-IL-6 antibody to the culture. IL-6 alone had no effect on MK colony formation. In the primary culture, MKs showed larger cell size and DNA content in the presence of both IL-3 and IL-6 than IL-3 alone. The replating experiments using immature MKs grown in the presence of IL-3 showed that IL-6 significantly augmented both cell size and DNA content. This effect was also neutralized by an anti-IL-6 antibody. IL-3 had no tangible effect on MK differentiation. Synergism between IL-6 and IL-3 on MK differentiation was not confirmed. These results suggest that IL-6 is a synergistic factor in the proliferation of MK progenitors and a direct effector of differentiation of immature MKs on in vitro human megakaryocytopoiesis.
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PMID:Interleukin-6 supports human megakaryocytic proliferation and differentiation in vitro. 191 78

Data concerning megakaryocytopoiesis and its regulation were summarized in this report. Critical analysis of these data indicates that: (i) megakaryocytopoiesis is a complex, multiple-stage cellular and biologic process; (ii) the survival, proliferation and differentiation of progenitor cells into immature megakaryocytes are regulated mainly by interleukin-3, granulocyte-macrophage colony-stimulating factor and an as yet uncharacterized megakaryocyte colony-stimulating factor, and the maturation of immature megakaryocytes to produce platelets is regulated primarily by interleukin-6 and thrombopoietin; (iii) optimal megakaryocyte development needs adequate interactions of several growth factors with target cell population and hematopoietic microenvironment; (iv) megakaryocytopoietic inhibition is controlled essentially by megakaryocyte-platelet products such as transforming growth factor-beta, and platelet factor 4 and its related proteins; interferon-alpha and -gamma also are able to play an inhibitory role; and (v) expansion or decrease of either normal or neoplastic megakaryocyte progenitor cells, change of platelet mass and abnormalities of growth factor levels in hematopoietic tissue might result in an abnormal megakaryocytopoiesis.
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PMID:Megakaryocytopoiesis: characterization and regulation in normal and pathologic states. 195 49

The in vivo effects of interleukin-3 (IL-3), interleukin-6 (IL-6), and a combination of IL-3 plus IL-6 on murine megakaryocytopoiesis and thrombopoiesis were examined. Human recombinant IL-6 was administered subcutaneously as 14 equal injections of 5,000 units each during a 102-hour period. Murine recombinant IL-3 was given as 8 injections of 80,000 units each during the first 54 hours. Megakaryopoiesis and thrombopoiesis were evaluated 120 hours after initial administration of the cytokines. Platelet levels increased by 20% following IL-3 alone, 35% following IL-6 alone and 61% after administration of both IL-3 and IL-6. Platelet production, as measured by 75Se-selenomethionine incorporation, increased by approximately 120% in animals that had received IL-6 or IL-3 plus IL-6. Megakaryocyte ploidy analysis by two-color flow cytometry showed a shift in the modal ploidy class from 16N to 32N and a significant increase in the frequency of 64N cells only in IL-6 treated animals. Both bone marrow and splenic megakaryocyte colony-forming cells were significantly increased following either IL-3 or IL-6. Bone marrow megakaryocyte size increased 18%, 43%, and 38%, respectively, after administration of IL-3, IL-6, or the combination of IL-3 plus IL-6. Leukocyte counts and hematocrits were unaffected by either cytokine. Additional groups of mice received the same injection schedule as above and the serial effects on peripheral blood cell levels were assessed for 30 days. Platelet levels, which had been elevated by IL-3 or IL-6, fell to control values within 4 days following the last injection. Animals given IL-6 or IL-3 plus IL-6 were subsequently thrombocytopenic relative to controls on days 7 through 9 following cessation of treatment. Temporary 'cycling' of platelet levels was observed for 3 weeks following treatment with IL-6 or the combination of IL-3 plus IL-6. We conclude that IL-6 and to a lesser extent IL-3 stimulate platelet production in vivo and that their combined effects on platelet levels are approximately additive. Following discontinuation of IL-3 or IL-6, the effects are rapidly reversed, presumably by negative feedback mechanisms, resulting in a period of 'rebound thrombocytopenia' in mice that had received IL-6.
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PMID:Multiple in vivo effects of interleukin-3 and interleukin-6 on murine megakaryocytopoiesis. 198 1

The in vivo effects of purified human recombinant interleukin-6 (IL-6) on murine megakaryocytopoiesis were examined. IL-6 was administered subcutaneously to Swiss Webster mice, followed by evaluation of bone marrow megakaryocyte ploidy, size and frequency, and median platelet volume 24, 48, and 72 hours after the initiation of IL-6 administration. In addition, bone marrow megakaryocyte morphology was examined using electron microscopy at 72 hours. IL-6 (10,000 U per subcutaneous injection) was administered three times during the first 24 hours, three times during the second 24 hours, and twice during the last 24-hour period. IL-6 bioactivity (10 U/ng) was determined using the IL-6-dependent murine hybridoma cell line B9. Megakaryocyte ploidy distribution, measured by two-color flow cytometry, demonstrated a shift in the modal ploidy class from 16N to 32N and a significant increase in the relative frequency of 64N megakaryocytes 48 and 72 hours (but not 24 hours) after initiation of IL-6 administration (cumulative doses of 60,000 and 80,000 U at 48 and 72 hours, respectively). In addition, ploidy levels were increased in animals that received a cumulative IL-6 dose of only 40,000 U (evaluated after 72 hours). The size of recognizable bone marrow megakaryocytes, determined by the cross-sectional areas of plastic embedded bone marrow megakaryocytes, was increased at the 48-hour (60,000 U IL-6) and 72-hour (80,000 U IL-6) time points. Megakaryocyte frequency, measured by flow cytometry, was unaffected at all time points and doses of IL-6. Median platelet volume, measured by electrical impedance, was not consistently altered by administration of IL-6. Electron microscopic examination of bone marrow megakaryocytes showed an increase in the proportion of megakaryocytes with a wide, peripheral, organelle-deficient zone from 20% +/- 9% (SD) in control animals to 50% +/- 7% (SD) (P less than .02) in animals that received IL-6. No changes were observed in the distribution of the demarcation membranes. IL-6 is a potent stimulator of murine megakaryocytopoiesis, in vivo, and appears to act early in megakaryocyte differentiation.
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PMID:Stimulation of megakaryocytopoiesis in mice by human recombinant interleukin-6. 198 2

Guinea-pig bone marrow megakaryocytes were isolated using an antibody to platelet glycoprotein Ib and a second antibody conjugated to magnetic beads. The procedure yielded an average of 644,800 megakaryocytes from two guinea-pigs with an average viability of 83%. All of the platelet glycoprotein Ib positive cells also expressed the platelet glycoprotein IIb-IIIa complex. The size and ploidy of megakaryocytes isolated by this technique were analysed in the presence of 10 ng/ml of interleukin-6 (IL-6). Without IL-6 megakaryocyte size increased significantly after 24 h, but an even larger increase in size occurred in the presence of IL-6. The modal ploidy class was 16N with an average of 19% 2N, 2.6% 4N, 16.4% 8N, 50.8% 16N and 11.1% 32N cells as determined by flow cytometry. Measurements made by microspectrophotometry were in close agreement. After 24 h incubation there was a significant rise in the percentage of 2N and 32N cells. The ploidy distribution after 24 h with IL-6 was the same as the control. Megakaryocytes cultured in the absence of serum on collagen gels did not form pseudopods and fragment, as occurs with serum (Leven et al, 1987). Addition of IL-6 to the serum-free cultures caused megakaryocytes to form extensive proplatelet extensions. We conclude that large numbers of pure guinea-pig bone marrow megakaryocytes can be isolated by immunomagnetic bead selection, including low ploidy immature megakaryocytes. Spontaneous maturation occurred as evidenced by the increase in megakaryocyte size and ploidy. IL-6 altered megakaryocyte size and morphology but not ploidy, indicating that these different characteristics of megakaryocytes may be regulated separately.
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PMID:Immunomagnetic bead isolation of megakaryocytes from guinea-pig bone marrow: effect of recombinant interleukin-6 on size, ploidy and cytoplasmic fragmentation. 201 49

The cytokine interleukin-6, which has been shown to be increased in patients with burn injuries, is produced by activated monocytes and endothelial cells and has many in vitro activities, including stimulation of acute-phase protein synthesis in hepatocytes, immunoglobulin synthesis in B lymphocytes, and stimulation of growth of megakaryocytes. In 13 patients with a mean of 31% full-thickness burns, we studied the relation of serum interleukin-6 to clinical parameters and parameters of the acute-phase response and immunoglobulin production. Interleukin-6 was already elevated within hours after the injury was sustained, and it remained elevated for several weeks. All components of the acute-phase response were observed: fever, tachycardia, leukocytosis with an associated left shift, elevation of C-reactive protein and alpha 1-antitrypsin, and a decrease in albumin levels. In the second week after burn injury, immunoglobulin M levels peaked, followed by a prolonged elevation of immunoglobulin G levels. Thrombocyte counts initially decreased and rebounded to supranormal levels after 2 weeks. Interleukin-6 levels were positively correlated with acute-phase responses. We believe that the production of interleukin-6 induces the synthesis of acute-phase proteins. High interleukin-6 levels may also be an etiologic factor in the marked immunoglobulin response observed. Likewise, the relation between the megakaryocyte-promoting activity of interleukin-6 and the rebound thrombocytosis requires further investigation.
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PMID:Interleukin-6 and its relation to the humoral immune response and clinical parameters in burned patients. 204 96

Multiple myeloma (MM) originates from the malignant clonal expansion of transformed B-lymphocytes (in which c-myc and ras oncogenes are probably involved). MM cells have a hybrid phenotype (with coexpression of the markers for both early and late B-differentiation and, sometimes, of T-lymphocyte, myelomonocyte, erythroid and megakaryocyte markers), which accounts for the association between MM and myeloproliferative disorders and for cytokine production. Interleukin-6 and immunologic control mechanisms regulate proliferation and differentiation into plasma cells secreting a monoclonal component (MC). Overt MM is diagnosed 1-2 years following malignant transformation. At this time, several aneuploid clones with resistant phenotype have been selected, and a small pool of actively cycling cells produces the great bulk (over 90%) of non proliferating tumor cells. The clinical and laboratory signs of MM arise from both tumor proliferation and MC damage to organs and organ systems. Tumor proliferation is mainly responsible for bone disease (since MM cells produce cytokines that activate the osteoclasts), inhibition of hemopoiesis and the appearance of plasma cell tumors. The MC causes renal failure, neurological signs, hemorrhagic manifestations. The prognosis for multiple myeloma is probably best estimated by two parameters, serum beta-2-microglobulin and the bone marrow labeling index. Induction therapy is still based on the use of alkylating agents, melphalan and cyclophosphamide, combined with prednisone. Second line treatment consists of VAD polychemotherapy or high-dose pulsed glucocorticoids. Many investigational approaches have been proposed, but their effectiveness awaits confirmation. In the absence of a curative regimen, much effort should be dedicated to the quality of supportive care. In this respect, bisphosphonates represent a new effective tool for the control of myeloma bone disease.
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PMID:Multiple myeloma. 208 Oct 91

N2-[(N-Acetylmuramoyl)-L-alanyl-D-isoglutaminyl-N6-stearoyl-L-lysine [MDP-Lys(L18), romurtide] is an immunopotentiating substance. In addition to neutrophilic leukocytosis, the effects previously found after the administration of this compound in both mice and humans were thrombocytosis and elevated levels of colony-stimulating factor (CSF) in peripheral blood. Although the exact mechanism of thrombopoiesis is not yet known, evidence has been accumulating that interleukin-6 (IL-6) plays an important role in the maturation of megakaryocytes, and the administration of IL-6 has been reported to induce a significant increase in blood platelets associated with promotion of megakaryocyte maturation. We measured the IL-6 levels in the culture supernatants of peripheral blood mononuclear cells (PBMCs), adherent cells and nonadherent cells in the presence of romurtide. Significant augmentation of IL-6 from PBMCs and adherent cells, but not nonadherent cells, was observed in the presence of romurtide in vitro.
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PMID:Production of interleukin-6 from macrophages by MDP-Lys (L 18), romurtide. 209 10

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