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

An analysis of the mechanism of generation of the soluble interleukin-6 receptor (IL-6R) has been performed. The membrane-bound receptor is proteolytically cleaved to release a soluble receptor form which retained its ligand binding capacity. Furthermore, the soluble IL-6R is unique in its ability to induce a biological signal in complex with the ligand interleukin-6 (IL-6) on cells which by themselves do not bind IL-6. Shedding of the IL-6R is strongly activated by PMA and can be inhibited by the protein kinase inhibitor staurosporine. The generation of the IL-6R is not dependent on protein synthesis. The inactive PMA analogue 4-alpha-phorbol-12,13-didecanoate fails to induce shedding of the IL-6R. Transfection of a protein kinase C expression plasmid into IL-6R expressing cells leads to enhanced shedding of the receptor. These experiments clearly show that protein kinase C regulates shedding of the IL-6R.
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PMID:Protein kinase C activity is rate limiting for shedding of the interleukin-6 receptor. 133 47

We studied the effect of cyclosporine A, prednisolone, and the Ca2+ channel blocker verapamil on interleukin-6 binding to mitogen-activated peripheral blood mononuclear cells, using a flow cytometric technique and phycoerythrin-conjugated IL-6. All mitogenic stimuli up-regulated IL-6 binding to a variable degree. PHA alone or in combination with PMA was the most effective stimulant in up-regulating IL-6 binding in all the experiments performed. The main changes in IL-6 binding were seen in the large cell cluster, which consisted mainly of lymphoblasts. PHA and PHA/PMA, however, also up-regulated the mean fluorescence intensity on the small cell cluster, which consisted mainly of quiescent lymphocytes. The overall effect of the three pharmacological agents on mitogen-up-regulated IL-6 binding was minimal; most significant were a down-regulation by all three agents of IL-6 binding by small lymphocytes in PHA/PMA cultures, a down-regulation of IL-6 binding by CsA in PHA/PMA-induced large PBMC, and an up-regulation by verapamil of PMA-induced IL-6 binding in large PBMC. Measurements of IL-2 binding and of IL-6 production in the same cultures showed a different pattern than that seen with IL-6 binding, as well as different CsA, prednisolone, and verapamil action. In conclusion, by using a new flow cytometric technique providing information both about the quantity of bound cytokine and about the proportion of IL-6-binding cells, we have demonstrated that IL-6 receptor expression in vitro by PBMC can be up-regulated by the use of stimulants differing in the signal transduction pathways they activate. In addition, by using different pharmacological agents and stimuli to dissect different activation pathways of the in vitro immune response, we conclude that IL-6R generation is regulated differently from IL-6 production. Furthermore, since CsA and prednisolone are known inhibitors of in vitro IL-2 production, our results indicate that IL-6R generation does not rely exclusively on the presence of IL-2.
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PMID:Binding of phycoerythrin-conjugated interleukin-6 to in vitro-activated human peripheral blood mononuclear cells--effect of immunosuppressive agents and of a calcium channel blocker. 149 42

Studying the production of IL-6 (interleukin-6) by monocytes, endothelial cells and smooth muscle cells we observed that cytokine inducers like IL-1, TNF alpha (tumor necrosis factor alpha), LPS (lipopolysaccharide), SAC (Staphylococcus Aureus Cowan 1) and PMA could be divided roughly into two categories. Bacterial products such as LPS or SAC have a potent IL-6 inducing effect on monocytes and minor or no effect on endothelial- and smooth muscle cells. The other category comprising IL-1, TNF alpha and PMA induces IL-6 production in endothelial- and smooth muscle cells. Only IL-1 induces IL-6 production in monocytes as well as in endothelial cells and smooth muscle cells. In addition to IL-6, also IL-1 and TNF alpha are produced by monocytes however with different kinetics. None of the stimuli had any inhibitory effect on IL-6 production with the exception of PMA. Whereas PMA induced IL-6 production in endothelial cells and it potentiated the induction of IL-6 by IL-1 in these cells, it inhibited LPS-stimulated IL-6 production in monocytes. In line with the effects of PMA, staurosporin induced IL-6 production in monocytes and it inhibited IL-1 driven IL-6 production by endothelial cells.
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PMID:Differential induction of interleukin-6 production in monocytes, endothelial cells and smooth muscle cells. 181 14

Using colony assays in semi-solid media, several investigators have shown that supernatants (SN) of normal and malignant human B-cells can stimulate the growth of granulocyte-macrophage (GM) progenitor cells. So far macrophage colony-stimulating factor (M-CSF) and interleukin-6 (IL-6) have been identified as potential colony-stimulating activity (CSA) present in B-cell SN. However, other CSAs such as GM-CSF, G-CSF, IL-1-beta, IL-3, and IL-4 may also be candidates in this respect. Several human B-cell lines (CL) were screened for the expression of the respective genes at the mRNA and protein level. Constitutive production of GM-CSF was detected in the lymphoblastoid CL Wi-L2-729-HF2 and in the Burkitt line Raji. The signal intensity of specific transcripts and the amount of protein being secreted increased upon exposure to the phorbol ester PMA. The hybridoma line HB-564 also expressed the GM-CSF gene, but required prior stimulation with PMA. 3H-thymidine incorporation of Raji and Wi-L2-729-HF2 cells was unchanged in the presence or absence of a specific neutralizing sheep anti-GM-CSF serum, suggesting that GM-CSF did not serve as an extracellular autocrine growth factor. The expression of the GM-CSF gene was independent of the proliferative state (log phase growth versus plateau phase growth) and of the presence of serum in cultures of the respective CL. The expression of G-CSF, IL-1-beta, IL-3, and IL-4 genes was not detectable in the CL at the mRNA level.
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PMID:Screening for expression of cytokines with hematopoietic growth factor activity by permanent human B-cell lines. 188 24

IL-6, which is also known as IFN-beta 2, hybridoma growth factor, hepatocyte-stimulating factor, and B cell differentiation factor, mediates acute phase responses including fever, has lymphocyte-stimulating capacities, and antiviral activity. IL-6 is produced by monocytes, fibroblasts, certain lymphocytes, and various tumor cells. The present study demonstrates that this multifunctional cytokine is released also by normal human epidermal cells (EC) and human epidermoid carcinoma cell lines (A431, KB). Accordingly, supernatants derived from freshly isolated EC, long term keratinocyte cultures, A431, or KB cells stimulated the proliferation of a hybridoma growth factor/IL-6-dependent plasmacytoma cell line (B9). IL-6 constitutively was produced in the presence of serum proteins. The addition of IL-1 alpha, IL-1 beta, or the tumor promoter PMA significantly enhanced the synthesis and release of EC-derived IL-6 (EC-IL 6). Like monocyte or fibroblast-derived IL-6, EC-IL-6 exhibited Mr microheterogeneity within 21 and 28 kDa. Similarly in Western blotting experiments an antiserum directed against human rIFN-beta 2/IL-6 detected the different Mr forms of EC-IL-6. Moreover, this antiserum was able to block the B9 cell growth-promoting capacity of EC-IL-6 strongly suggesting that this EC-derived mediator is closely related, if not identical with IL-6. This was further confirmed by Northern blot analysis detecting IL-6 specific mRNA both in long term cultured keratinocytes and A431 cells by hybridization with a cDNA fragment encoding for B cell differentiating factor 2/IL-6. Therefore, in addition to the production of other cytokines as previously reported, EC and in particular keratinocytes also synthesize and release IL-6. This further supports the important regulatory role of the epidermis during the pathogenesis of inflammatory, autoimmune, and neoplastic diseases.
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PMID:IFN-beta 2, B cell differentiation factor 2, or hybridoma growth factor (IL-6) is expressed and released by human epidermal cells and epidermoid carcinoma cell lines. 278 42

CD28 is an Ag of 44-kDa Mr that is expressed on the membrane of the majority of human T cells and that is recognized by mAb 9.3. The functional effects of mAb 9.3 on peripheral blood T cells were studied. mAb 9.3 was not mitogenic, unless it was combined with PMA. When CD28 was cross-linked after binding of mAb 9.3 to the T cell by immobilized or soluble anti-mouse IgG, T cells proliferated in response to rIL-2, provided that monocytes were also present. The additional signal required for IL-2 responsiveness after cross-linking of CD28 could also be delivered in cultures of purified T cells by a cellfree monocyte culture supernatant. Expression of IL-2R on about 10% of the T cells was demonstrated by staining with an anti-IL-2R mAb, and was found to be largely restricted to CD4+ cells. The active compound responsible for the helper signal in the monocyte culture supernatant was identified as IL-6 because purified IL-6 (but not IL-1 beta) had similar activity and because an antiserum to IL-6 (but not an antiserum to IL-1 beta) neutralized the activity of the monocyte supernatant and blocked T cell proliferation. An anti-IL-2R antibody also completely inhibited T cell proliferation induced by the combination of mAb 9.3, IL-2, and IL-6. Our results provide evidence that cross-linking of CD28 induces functional IL-2R and that this activity is dependent on a helper signal provided by monocytes, more specifically IL-6. Moreover, our results indicate that IL-6 (previously called B cell stimulatory factor-2) is active on T cells. If a natural ligand for CD28 can be identified, the mechanism of induction of IL-2 responsiveness described here might explain how T cells become nonspecifically involved in an ongoing cellular immune reaction.
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PMID:Cooperation between an anti-T cell (anti-CD28) monoclonal antibody and monocyte-produced IL-6 in the induction of T cell responsiveness to IL-2. 326 51

The insulin secreting rat Rinm5F cells are often used to study the cytotoxic actions of interleukin-1 (IL-1) on pancreatic beta-cells. We demonstrate here that Rinm5F insulinoma cells express both type I and type II interleukin-1 receptor (IL-1R) mRNAs and gene products. IL-1R agonists, recombinant murine IL-1 alpha (rmIL-1 alpha, 10 ng/ml) and recombinant rat IL-1 beta (rrIL-1 beta, 100 pg/ml or 10 ng/ml) induce the upregulation of mRNA expression for both types of IL-1 receptors (IL-1Rs). This effect of rrIL-1 beta is antagonised by preincubation with recombinant human interleukin 1 receptor antagonist protein (rhIL-1ra, 5 micrograms/ml). Furthermore, this rrIL-1 beta induced upregulation of IL-1R mRNAs is blocked by actinomycin D (7.5 micrograms/ml), whereas cycloheximide (20 micrograms/ml) has no effect. The phorbol ester PMA (20 nM) upregulates the expression of mRNAs both IL-1 receptors, whereas glucose (50 mM) upregulates the expression of the type I IL-1R mRNA only. Pretreatment of cells with pertussis toxin (100 ng/ml) partially blocks the rrIL-1 beta induced expression of mRNA for the type I and, to a lesser extent, the type II IL-1R. Incubation of the cells with rrIL-1 beta also induces a time-dependent expression of c-fos, interleukin-6 (IL-6) and tumour necrosis factor alpha (TNF-alpha) mRNAs. Binding studies with 125I-recombinant human IL-1 beta (125I-rhIL-1 beta) indicate that IL-1R gene products, with the ligand binding characteristics of the type I IL-1R, are constitutively present on Rinm5F cells. Treatment with rrIL-1 beta (6h) increases the number of 125I-rhIL-1 beta binding sites on Rinm5F cells. We have also demonstrated that the number of type II IL-1R binding sites increases after induction with rrIL-1 beta (6h), by indirect immunofluorescence using a monoclonal antibody (ALVA 42) raised against the human type II IL-1R. Furthermore, we have sequenced the type II IL-1R cDNA in the rat insulinoma Rinm5F cells. The comparison of the amino acid sequence of the rat type II IL-1R with that of the mouse and human type II IL-1Rs shows 90% and 62% amino acid identity, respectively. The most important difference between the human and murine type II IL-1Rs, and this rat type II IL-1R cDNA, is an open reading frame coding for a six amino acid longer, strongly charged (QIKEMK), cytosolic domain.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Interleukin-1 stimulates the expression of type I and type II interleukin-1 receptors in the rat insulinoma cell line Rinm5F; sequencing a rat type II interleukin-1 receptor cDNA. 752 17

In vitro treatment of human peripheral blood mononuclear cells (PBMNC) with proteolytic enzymes (bromelain, papain) and amylase leads to the production of large amounts of tumor necrosis factor-alpha (TNF-alpha), interleukin-1-beta (IL-1 beta), and interleukin-6 (IL-6) in a time and dose dependent manner. Increased TNF-alpha and IL-6 production was already found after 4-6 hours of incubation, and plateau levels were reached after 12-16 hours. Plateau levels up to 1500 pg TNF-alpha/ml/10(6) PBMNC, 13000 pg IL-1 beta/ml/10(6) PBMNC, and 23000 pg IL-6/ml/10(6) PBMNC were observed. Control cultures contained below 35 pg/ml/10(6) PBMNC of TNF-alpha, IL-1 beta or IL-6. In contrast to TNF-alpha which was undetectable after more than 24 hours, peak levels of IL-1 beta and IL-6 were still present at 24 hours. After incubation of the enzyme solution for some hours at 56 degrees C the cytokine inducing capacity disappeared. Neutralization experiments with inactivating antibodies, radioimmunoassay, and western blotting after electrophoretic separation showed that the TNF-like activity found in the lytic assay was due to TNF-alpha. Interferon-alpha (IFN-alpha) and Interferon-gamma (IFN-gamma), which had no effect alone, synergistically increased TNF-alpha production when applied together with the enzymes. A commercial mixture of these enzymes (Wobenzym), which was also investigated, showed a similar concentration and time dependence, as well as synergism with the interferons. A synergistic effect on TNF-alpha production was also found with the enzymes and phorbol ester (PMA).
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PMID:Proteolytic enzymes and amylase induce cytokine production in human peripheral blood mononuclear cells in vitro. 752 14

The influence of peplomycin (PLM) and azelastine hydrochloride (Azeptin) on reactive oxygen (RO) and cytokine generation was examined in human peripheral blood mononuclear leukocytes, polymorphonuclear leukocytes (PMN), and rabbit alveolar macrophages (RAM). In addition, the influence of these drugs on DNA and collagen synthesis was investigated in human gingival and rabbit pulmonary fibroblasts. In vitro, PLM increased the FMLP- and PMA-induced chemiluminescence and superoxide (O2-) generation in human PMN and RAM in a dose-dependent manner. In contrast to PLM, Azeptin dose-dependently suppressed RO generation. Such contrasting actions of PLM and Azeptin were also observed in RAM and PMN obtained from rabbits treated with PLM or Azeptin. Even when human PMN were preincubated with 10-100 micrograms/ml of PLM, the increase in RO generation was negligible in the presence of 10(-5) M Azeptin in the culture medium. No increases in RO generation were observed in RAM or PMN obtained from rabbits that had received PLM (0.1 mg/kg per day) and Azeptin (0.04 mg/kg per day) concomitantly. PLM suppressed superoxide dismutase activity in RAM and human PMN, while Azeptin did not affect this activity. In vitro, PLM up-regulated the release of interleukin-1 beta, interleukin-6, tumor necrosis factor alpha, and granulocyte-macrophage colony-stimulating factor both from human cells and from RAM and pulmonary fibroblasts. In the generation of these cytokines, Azeptin abrogated the up-regulatory action of PLM. PLM and Azeptin also had contrasting actions in [3H]thymidine and [3H]proline incorporation in human and rabbit fibroblasts. Furthermore, protein tyrosine phosphorylation, in particular that of a 115-kDa protein in human PMN, was suppressed by Azeptin and enhanced by PLM. These results seem to indicate that up-regulated RO and collagen generation are the causative factors of PLM-induced pulmonary fibrosis and that Azeptin may suppress the adverse effect.
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PMID:Contrasting influence of peplomycin and azelastine hydrochloride (Azeptin) on reactive oxygen generation in polymorphonuclear leukocytes, cytokine generation in lymphocytes, and collagen synthesis in fibroblasts. 780 82

The influence of OK-432, a streptococcal preparation, on human polymorphonuclear leukocytes (PMN) was examined. OK-432 increased O2- generation was also observed when PMN were cultured with 10(-2)KE/ml OK-432 for 1 h and then stimulated with phorbol myristate acetate or formyl-metionyl-leucil-phenylalanine (FMLP). In addition, PMN O2- generation was promoted by culture supernatants of peripheral blood mononuclear cells (PBMC) incubated with 10(-3) or 10(-2) KE/ml OK-432. Furthermore, OK-432 (10(-3)-10(-2) KE/ml) enhanced the chemiluminescence of FMLP- and PMA-stimulated PMN. However, nitroblue tetrazolium reduction and myeloperoxidase activity were only minimally enhanced. Not only the candidacidal activity of PMN but also antibody-dependent cell-mediated cytotoxicity against Candida and Raji cells were enhanced in correspondence with the increased generation of reactive oxygen species. Culture of PMN or PBMC for 24 h with OK-432 resulted in a concentration-dependent increase in the substantial production of interleukin-1 beta, interleukin-6 and tumor necrosis factor-alpha. OK-432 also enhanced granulocyte-macrophage colony stimulating factor and gamma-interferon generation by leukocytes in a dose-dependent manner. Our research indicates that OK-432 enhances PMN function directly as well as via the promotion of cytokine production, and suggests that these effects of OK-432 could be beneficial in immunosuppressed patients.
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PMID:Enhancement of polymorphonuclear leukocyte (PMN) function by OK-432. 815 May 58


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