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

Interleukin-6 (IL-6) induced increased, leukocyte and platelet counts on around day 20 when it was administered into [BALB/c-->C3H/He] bone marrow chimeras from day 1 to day 12. Increased leukocyte counts and hemoglobin (Hb) levels were also observed at around day 60 and from day 41 to 80, respectively. On the other hand, hematopoietic recovery in [C3H/He-->C3H/He] bone marrow chimeras injected with IL-6 was different from that in [BALB/c-->C3H/He] bone marrow chimeras, showing no delayed and long-lasting increase in Hb levels but showing an early and transient increase in Hb levels and platelet counts. Sera from [BALB/c-->C3H/He] bone marrow chimeras injected with IL-6 showed predominant productions of IL-3 and/or IL-4. Reverse transcriptase polymerase chain reaction (RT-PCR) showed that stem cell factor (SCF) mRNA expression was increased in bone marrow or spleen cells from [BALB/c-->C3H/He] bone marrow chimeras injected with IL-6 on day 36. Furthermore, we analyzed influence of IL-6 on graft-versus-host disease (GVHD) in [BALB/c-->C3H/He] bone marrow chimeras injected with IL-6. Decreased survival days and body weights were not observed when compared with the control. Histopathological changes of the liver due to GVHD were also not obvious. However, alloreactive mixed lymphocyte reactions (MLRs) were readily detected although cytotoxic T cells were not generated. Since H-2 typing showed that donor-type chimerism was predominantly observed, it was suggested that split tolerance might be induced by IL-6 administration. Increased IL-2 levels were not detected in sera from [BALB/c-->C3H/He] bone marrow chimeras injected with IL-6 whereas IL-4 was detected in the same sera, indicating that type 2 helper T (TH2) cells appeared to be predominantly generated. These results suggest that IL-3/IL-4 and SCF appeared to synergistically support delayed effects on hematopoiesis in [BALB/c-->C3H/He] bone marrow chimeras injected with IL-6 although early effects appeared to be mediated mainly by IL-6 directly or indirectly. Furthermore, IL-6 could induce split tolerance in [BALB/c-->C3H/He] bone marrow chimeras via a preferable activation of TH2 type cells without inducing severe GVHD.
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PMID:In vivo administration of interleukin-6 in murine allogeneic bone marrow chimeras: early and delayed enhancement of hematopoiesis accompanied with split tolerance but not with graft-versus-host disease. 798 20

To better understand the effects of freezing on various immunocompetent cell functions, the interleukin-6 (IL-6)-producing activities of frozen peripheral blood mononuclear cells (PBMCs) from healthy subjects were determined. Frozen, lipopolysaccharide (LPS)-activated PBMCs produced significantly larger quantities of IL-6 than fresh cells. Although elimination of radiosensitive, CD8+ suppressor T cells had no significant effect on PHA-induced IL-6 production by T cells, elimination of CD4+ Leu-8+ suppressor T cell subsets resulted in a significantly enhanced IL-6 secretion. Exogenous addition of prostaglandin E-2 to frozen PBMCs and monocytes inhibited LPS-induced IL-6 production. The results suggest that functional inactivation of a subset of cryosensitive, PGE-2-secreting monocytes is associated with an increase in IL-6 production by the other subset. They also indicate that a subset of CD4+ Leu-8+ T cells might be involved in feedback inhibition of PHA-induced T cell-mediated IL-6 production. The results provide further evidence that the presence of larger quantities of IL-6 in conjunction with increased amounts of IL-1 and IL-2 secreted by the frozen cells may be responsible for the previously reported enhanced immunoglobulin-producing abilities of frozen cells from clinically healthy subjects and from patients with lung cancer.
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PMID:Effects of cryopreservation on immune responses: VII. Freezing induced enhancement of IL-6 production in human peripheral blood mononuclear cells. 798 56

The supernatant of a cell line of squamous cell carcinoma of the head and neck (SCCHN), PCI-50, was previously shown to induce activation, promote proliferation and increase antitumor cytotoxicity of freshly purified human natural killer (NK) cells and CD4+ T lymphocytes [Arch Otolaryngol Head Neck Surg (1994) in press]. This supernatant was found also to promote the growth of a variety of hematopoietic cell lines, including Jurkat, THP-1, K562, NK-92 or Epstein-Barr-virus-transformed B cell lines. The Jurkat cell line was selected as a reporter cell in an 18-h proliferation assay established to measure the growth-promoting activity of PCI-50 supernatant. The presence of soluble tumor-derived factors able to induce proliferation of Jurkat cells was demonstrated in the supernatant produced by several other SCCHN cell lines but not in that produced by a gastric cancer cell line (HR) or renal cell carcinoma line (5117G8). The growth-promoting PCI-50 supernatant was shown to contain 28 +/- 0.5 pg/ml interleukin-6 (IL-6) in vitro but was negative for interferon gamma, IL-1, IL-2, IL-4, tumor necrosis factor alpha, granulocyte/macrophage-colony-stimulating factor and IL-12. The addition of any of these recombinant cytokines to Jurkat cell cultures did not significantly promote growth, while PCI-50 supernatant was consistently growth-stimulatory. This supernatant neither enhanced intracellular Ca2+ concentration in Jurkat cells nor induced up-regulation of activation antigens on the cell surface, although it supported growth of Jurkat cells in the absence of IL-2. The growth-promoting activity in the PCI-50 supernatant was acid-labile at pH 2 for 4 h, heat-resistant at 96 degrees C for 1 h and sensitive to treatments with trypsin and pepsin. Preincubation of the PCI-50 producer cells with tunicamycin or cyclohexamide reduced the level of growth-promoting activity in the supernatant. A partial purification of this activity was achieved using Amicon filtration, chromatography on concanavalin-A-Sepharose and then a hydroxyapatite column and high-pressure liquid chromatography gel filtration. The partially purified glycoprotein had a molecular mass of 50-70 kDa, as determined by gel filtration.
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PMID:Proliferation of hematopoietic cell lines induced by a soluble factor derived from human squamous cell carcinomas of the head and neck. 800 Oct 29

Propionibacterium acnes (P. acnes) was isolated in high rates and in high concentrations from lymph nodes in patients with sarcoidosis. However, the precise mechanism of granuloma formation and immunomodulation by P. acnes has not been elucidated yet. In patients with sarcoidosis, it was found that the high levels of interleukin-2 released from alveolar lymphocytes as well as interleukin-1, tumor necrosis factor and interleukin-6 released from alveolar macrophages were stimulated by P. acnes. These cytokines (mainly IL-2), released by P. acnes in large quantities, play a major role in the compartmentalization of the T-cell population in the lung and lead to the formation of alveolitis and granuloma in the lung parenchyma of patients with sarcoidosis.
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PMID:[Sarcoidosis and Propionibacterium acnes]. 804 29

Interleukin-6 (IL-6) participates in a variety of cellular activities including regulation of immune and inflammatory responses. We have previously reported a discrepancy between bioactive and antigenic IL-6 secretion by lipopolysaccharide-stimulated alveolar macrophages (AMs) from smokers and have speculated that this may be due to cosecretion of an IL-6 inhibitor. In this study we further define our methods for measuring IL-6 inhibitory activity by testing the ability of serially diluted, cultured cell supernatants and lysates to suppress proliferation of an IL-6-dependent cell line, B9, to optimal concentrations of rIL-6. AM secretion of the inhibitory factor was optimal when AMs were stimulated with 1 micrograms/ml lipopolysaccharide (LPS). AMs from smokers secreted significantly greater amounts of this factor than AMs from nonsmokers. It was crucial to remove IL-6 from test samples on an IL-6 immunoaffinity column before analyzing for IL-6 inhibitory activity because (1) B9 cell proliferation could be suppressed by excess amounts of IL-6 in test supernatants and (2) excess rIL-6 added to the inhibitor assay reduced inhibitory activity. The latter finding suggested that IL-6 inhibitory activity was due to a competitive inhibitor of IL-6. This factor was shown to be specific for IL-6, because no inhibitory activity was seen on IL-2- or IL-4-dependent cell lines. Finally, we demonstrated that monocytes could also secrete an inhibitor of IL-6 bioactivity. However, secretion appeared to be less than that observed by AMs, suggesting that differentiation of monocytes into macrophages upregulated production of this factor.
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PMID:Measurement of IL-6 inhibitory activity in cultured cell supernatants and lysates. 805 93

The simian immunodeficiency virus SIVsmmPBj14 (SIV-PBj14) is an atypical lentivirus that causes acute disease and death in pig-tailed macaques and in vitro replicates efficiently in resting macaque lymphocytes and activates and induces proliferation of lymphocytes. The present study was conducted to test the hypothesis that production of large quantities of SIV-PBj14 induces widespread immune activation and elaboration of cytokines which lead directly to the death of infected pig-tailed macaques. Following intravenous inoculation of pig-tailed macaques with SIV-PBj14, acute disease developed and was characterized by high levels of plasma viremia, p27gag antigenemia, tumor necrosis factor alpha, and interleukin-6 (IL-6). All animals died within 10 days of infection, at which time some animals had as many as 100% CD4+ cells in the periphery and lymphoid tissues infected. During the last few days before death, titers of infectious virus in blood increased as much as 10(5)-fold. By using dual-label immunofluorescence assays for detection of cell surface activation markers, both CD4+ and CD8+ lymphocytes were shown to express the IL-2 and transferrin receptors following either in vivo or in vitro infection with SIV-PBj14. Furthermore, in vitro infection of quiescent macaque lymphocytes by SIV-PBj14 was accompanied by proliferation of both CD4+ and CD8+ lymphocyte subsets, as measured by incorporation of [3H]thymidine. Increases in numbers of activated lymphocytes and levels of proinflammatory cytokines in plasma coincided with increased amounts of detectable virus in vivo. Clinical signs of disease and pathologic findings were most consistent with death from a shock-like syndrome, in which acute-phase inflammatory cytokines are known to play a major role. Tumor necrosis factor alpha, IL-2, and IL-6 were detected in some cultures infected with SIV-PBj14, but this finding was not consistent. When cytokines were detected, their concentrations were essentially no different from those found in control cultures infected with SIVsmm9, a prototypic strain from which SIV-PBj14 was derived. The in vivo results suggest a synergistic cycle of activation of lymphocytes and monocytes, elaboration of cytokines, and virus production that accelerates uncontrolled and culminates in death. The observed correlations between in vivo and in vitro activation events following SIV-PBj14 infection validate the use of in vitro studies to clarify lentivirus-lymphocyte interactions that may contribute to the virulence of SIV-PBj14.
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PMID:Immune activation and viral burden in acute disease induced by simian immunodeficiency virus SIVsmmPBj14: correlation between in vitro and in vivo events. 805 36

Leukemia inhibitory factor (LIF), similar to interleukin-6 (IL-6), is a glycoprotein growth factor and differentiation regulator that has pleiotropic activity in several cellular systems. Recent reports of constitutive IL-6 production from spontaneously proliferating cells from human T-cell leukemia virus (HTLV)-infected individuals led us to examine the expression of IL-6 and LIF during HTLV infection. In vitro infection of peripheral blood lymphocytes with HTLV-I was associated with production of both soluble LIF and IL-6 in conjunction with the increasing HTLV antigen concentration. Northern blot analysis of T-cell lines generated from individuals infected with HTLV-I (MT-2, HuT-102, FS, EG, SP) and HTLV-II (Mo-T, H2A, H2E) demonstrated a marked increase in constitutive expression of LIF and IL-6 transcripts, as compared with uninfected cell lines (HuT-78, Jurkat). The constitutive expression of LIF and IL-6 was independent of presence of IL-2 in the culture medium, as both IL-2-independent (MT-2, HuT-102, SP, Mo-T) and IL-2-dependent (FS, EG, H2A, H2E) cell lines expressed LIF and IL-6 transcripts. Furthermore, LIF and IL-6 RNA expression in an HTLV-I-infected cell line (MT-2) was enhanced by phorbol ester stimulation via mechanisms that appear to be dependent on the posttranscriptional regulatory controls. These results show that both LIF and IL-6 are produced by HTLV-I- and HTLV-II-infected cells, which could potentially alter the transcriptional regulation of HTLV gene expression by inducing certain early response genes.
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PMID:Infection with human T-lymphotropic viruses leads to constitutive expression of leukemia inhibitory factor and interleukin-6. 809 6

We have recently shown that a single transfusion of red blood cells to normal human volunteers significantly increases the secretion of a variety of cytokines. In the present study we explored the in vitro effect of whole red blood cells on various T cell and monocytes functions of autologous human or mouse origin. This in vitro model would allow us to further determine in future studies the membranal determinants or the intracellular products of the RBC responsible for the enhancing effect. We demonstrate in this study that addition of autologous erythrocytes to human mononuclear cells or mouse spleen cell cultures results in enhancement of cellular responses to suboptimal concentrations of mitogens. These include cell proliferation, the secretion of IL-2, colony stimulating factor (CSF), interferon-gamma, tumor necrosis factor, and interleukin-6 by human MNC, and cell proliferation, IL-2, IL-3, and CSF by mouse spleen cells. The enhancing effect was dose dependent. Moreover, RBC are shown to directly enhance the expression of IL-2 receptors on both human and mouse cells without the need for the presence of mitogenic stimulation. The expression of IL-2R was measured both by acquisition of responsiveness to exogenous recombinant IL-2 and by immunofluorescence staining. We suggest that whole red blood cells exert a general enhancing effect on the secretion of a variety of cytokines and induce IL-2 receptor expression, probably through nonspecific interaction between membranal domains on erythrocytes and CD2 antigen on T cells.
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PMID:Enhancing effects of autologous erythrocytes on human or mouse cytokine secretion and IL-2R expression. 809 64

The basophilic leukaemia cell line KU812 can be induced to differentiate into basophil-like cells in vitro when exposed to supernatant from the Mo T-cell line. KU812 cells express affinity receptors for IgE, produce histamine and tryptase and have the capacity for IgE-mediated histamine release. In this study we have examined the cytokines, produced by the Mo cell line, which are responsible for the observed differentiation-inducing effect in the KU812 cell line. It was shown that interleukin-6 (IL-6) and tumour necrosis factor-alpha (TNF-alpha) induced differentiation in the KU812 cells and that these cytokines were responsible for the differentiation-inducing effect of the Mo supernatant. Other cytokines tested, IL-1 beta, IL-2, IL-4, IL-5, IL-8, granulocyte-macrophage colony-stimulating factor (GM-CSF) and nerve growth factor (NGF) were without effect on the KU812 cells. KU812 was also shown to express receptors for both TNF-alpha and IL-6 after 3 days cultivation with conditioned media from the Mo T-cell line. Untreated cells showed no detectable levels of TNF-alpha or IL-6 receptors indicating induction of these receptors during differentiation. Spontaneous differentiation was shown to occur under serum-free conditions which may be the result of endogenous IL-6 production through an autocrine loop. The activity of TNF-alpha and IL-6 could be blocked by specific monoclonal antibodies (mAb) to the respective cytokine.
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PMID:TNF-alpha and IL-6 induce differentiation in the human basophilic leukaemia cell line KU812. 813 23

We have previously reported that transforming growth factor-beta 1 (TGF-beta 1) inhibits interleukin-6 (IL-6) induction by IL-2 and IL-1 in fresh human monocytes. We investigated the effects of TGF-beta 1 on the expression of tumoricidal activity induced by IL-2 or interferon-gamma (IFN-gamma) in human monocytes. We showed that TGF-beta 1 specifically inhibited, in a dose-dependent manner, IL-2-induced but not IFN-gamma-induced monocyte tumoricidal activity. The inhibitory effects of TGF-beta 1 on IL-2-activated monocytes were not caused by down-modulation of the IL-2 receptor beta (IL-2R beta) because the treatment of monocytes with IL-2 and TGF-beta 1 increased IL-2R beta mRNA expression. However, we found that TGF-beta 1 down-modulated IL-2-induced IL-2R gamma mRNA, which may be responsible for the TGF-beta 1 inhibition of monocyte activation by IL-2. The resistance of the IFN-gamma-induced activation to the inhibitory effects of TGF-beta 1 could be caused by the ability of IFN-gamma to decrease TGF-beta 1 receptor expression, as shown by cross-linking experiments. Overall, these results showed that TGF-beta 1 is a powerful inhibitor of IL-2- but not of IFN-gamma-induced activation of monocytes to a cytotoxic stage. This differential effect may be attributed to modulation of cytokine receptor expression.
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PMID:Inhibitory cytokine circuits involving transforming growth factor-beta, interferon-gamma, and interleukin-2 in human monocyte activation. 819 69


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