Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:2.7.7.49 (reverse transcriptase)
31,746 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In vitro immune responses to Legionella pneumophila were investigated. When human peripheral blood lymphocytes (PBL) from healthy volunteers were stimulated with formalin-killed L. pneumophila for 7 days in vitro, strong proliferative responses were observed. The responding cells were shown to be a CD4 T cell subset. It was also found that the CD4 T cells secreted significant amounts of IFN-gamma into the PBL culture supernatant. The production of IFN-gamma and IL-4 by PBL was measured semiquantitatively by reverse transcriptase-assisted polymerase chain reaction (RT-PCR) methods. Formalin-killed or live L. pneumophila-stimulated PBL expressed the mRNA for IFN-gamma but not the mRNA for IL-4. The results suggest that the whole bacterium, as opposed to the supernatant, predominantly stimulates Th1 type helper T cells. The cloned T cells specific for L. pneumophila expressed the mRNA for IFN-gamma but not for IL-4. In contrast to formalin-killed or live L. pneumophila stimulation, when PBL were stimulated with the bacterial culture supernatant, the proliferating T cells produced the mRNA for IL-4 as well as for IFN-gamma. A significant correlation between the proliferative response to formalin-killed L. pneumophila and IFN-gamma release in culture was observed (r = 0.6932, P < 0.001) in PBL from 30 healthy volunteers. From these in vitro studies, it is suggested that the whole L. pneumophila bacterium and their soluble antigens stimulate T cells in a manner which results in a different pattern of cytokine production.
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PMID:Interferon-gamma (IFN-gamma) production by human T lymphocytes upon Legionella pneumophila stimulation in vitro. 781 13

The inflammatory cytokines IFN-gamma and TNF-alpha have been demonstrated in various autoimmune diseases, and are thought to participate in the induction and pathogenesis of disease. TFN-alpha is a cytopathic cytokine that is cytotoxic for oligodendrocytes in vitro and has been implicated in the pathology of multiple sclerosis and its animal model experimental allergic encephalomyelitis (EAE). We used reverse transcriptase (RT)-PCR to study the kinetics, cellular source, and regulation of cytokine gene expression in the central nervous system (CNS) of SJL/J mice with myelin basic protein-induced EAE at different stages of the disease. The expression of CD3, IL-2, IFN-gamma, and TNF-alpha mRNA was barely detectable in the CNS of unmanipulated mice or mice that were immunized with adjuvant but showed no symptoms. These mRNAs were readily detectable in the CNS of mice during peak disease, then coordinately dropped to background levels during remission. Analysis of cells isolated from the CNS of mice with acute EAE showed that the Th1 cytokines, IL-2 and IFN-gamma, were produced by infiltrating CD4+ T cells. In contrast, TNF-alpha was predominantly transcribed by non-T mononuclear CNS cells, the majority of which were identified as microglia and macrophages by their Mac-1 phenotype. Microglia could be discriminated by their low expression of CD45. Incubation of freshly derived, adult microglia from normal, uninfiltrated, CNS with activated Th1 supernatant induced the production of TNF-alpha mRNA. Therefore, TNF-alpha is made by both CNS-resident microglia and infiltrating macrophages during EAE, and this production is tightly controlled by cytokines secreted by infiltrating CD4+ T cells.
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PMID:TNF-alpha expression by resident microglia and infiltrating leukocytes in the central nervous system of mice with experimental allergic encephalomyelitis. Regulation by Th1 cytokines. 781 94

The expression of the cytokine genes in normal placenta was studied using RT-PCR method capable of detecting low levels of mRNA. Total RNA was prepared from placenta of specific pathogen-free BALB/c mice at the 16th day of gestation by acid guanidinium thiocyanate-phenol-chloroform (AGPC) method. cDNA was synthesized by M-MLV reverse transcriptase, and amplified using the specific oligonucleotide primers for IL-1, IL-2, IL-3, IL-4, IL-5, IL-6, TNF-alpha, IFN-alpha, IFN-beta and IFN-gamma by PCR method. IL-1 beta, IL-6, TNF-alpha, IFN-alpha, IFN-beta and IFN-gamma mRNA were detected in all the placentas tested. On the other hand, the expressions of IL-2, IL-3, IL-4, and IL-5 mRNA were not detected at all. These results suggest that these cytokines may play a role in the evolution of pregnancy.
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PMID:[Expression of cytokine messenger RNA in murine placenta]. 783 98

The expression of the cytokine genes in human spleen was studied using reverse transcriptase-polymerase chain reaction (RT-PCR) method capable of detecting low levels of mRNA. Total RNA was prepared from human spleen by acid guanidinium thiocyanate-phenol-chloroform (AGPC) method. cDNA was synthesized by M-MLV RTase using oligo (dT)16 primer, and amplified using the oligonucleotide primers specific for IL-1 alpha, IL-1 beta, IL-2, IL-3, IL-4, IL-5, IL-6, IL-7, IL-8, IL-9, TNF-alpha, IFN-alpha, IFN-beta and IFN-gamma by PCR method. Although IL-1 beta, IL-4, IL-5, IL-6, IL-7, IL-8, TNF-alpha, IFN-alpha and IFN-gamma mRNA were detected in all the samples tested, IL-3 and IFN-beta mRNA was not detected at all. These results suggest that many kinds of cytokines may be produced constitutionally in human spleen, and its pattern of cytokine production was similar to that in mice.
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PMID:[Expression of cytokine messenger RNA in human spleen]. 783 9

We noted previously that ischemic acute tubular necrosis (ATN) induces local expression of MHC products in renal epithelium. The present investigations were conducted to establish the role of IFN-gamma in the regulation of MHC antigen expression in ATN and to explore the changes in cytokine and growth factor expression induced by ischemic renal injury. We produced unilateral ischemic ATN in mice by clamping the left renal pedicle. MHC class I and II steady state mRNA induction was assessed by northern blot analysis, and MHC product was quantified by the extent of binding of radiolabeled monoclonals to tissue homogenates. The steady state mRNA levels for IFN-gamma, IL-2, IL-10, and granulocyte-macrophage CSF were assessed by reverse transcriptase polymerase chain reaction and the levels for transforming growth factor-beta 1 and prepro-epidermal growth factor (ppEGF) were assessed by Northern blot analysis. In the injured kidneys, steady state mRNA levels for IFN-gamma, IL-2, IL-10, granulocyte-macrophage CSF, and transforming growth factor beta-1 were increased, whereas ppEGF mRNA was markedly decreased. The MHC expression was inhibited by treatment of mice with an anti-IFN-gamma mAb (R4-6A2). Murine EGF, administered in an attempt to accelerate recovery, did not reduce the cytokine and MHC changes. These data indicate that ischemic injury, and possibly other forms of injury, triggers a complex circuit of proinflammatory cytokines. This "injury response" could be relevant to clinical renal transplants, where ATN is associated with poor graft outcome.
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PMID:Ischemic acute tubular necrosis induces an extensive local cytokine response. Evidence for induction of interferon-gamma, transforming growth factor-beta 1, granulocyte-macrophage colony-stimulating factor, interleukin-2, and interleukin-10. 787 62

By using superantigens, we have found previously that keratinocytes activated by IFN-gamma could serve as accessory cells, providing costimulatory signals needed to induce T cell proliferation. Here, we compared the profile of cytokines produced by T cells stimulated in the presence of activated keratinocytes with the response seen using professional APCs. When keratinocytes are used as accessory cells there is a specific defect in T cell IFN-gamma production, whereas IL-2 and IL-4 are induced at levels comparable with those seen when professional APCs are used as accessory cells. Because keratinocytes express BB-1, a CD28-ligand distinct from B7-1 or B7-2 (which are found on professional APCs), we examined the possibility that the defect in IFN-gamma production might be a result of nonproductive CD28 engagement. However, even when the CD28 pathway is directly activated by a stimulatory mAb, there is no induction of IFN-gamma production in keratinocyte-supported cultures. In these same cultures IL-2 production is increased 10-fold, thus demonstrating a specific deficiency in the induction of IFN-gamma rather than a failure to respond to CD28 stimulation. Analysis by reverse transcriptase-PCR and ELISA for the inducible p40 chain of IL-12 reveals that keratinocytes produce little if any messenger RNA and no protein for IL-12 p40 compared with professional APCs. Addition of rIL-12 to keratinocyte-supported cultures restores IFN-gamma levels to those seen when professional APCs are present. Finally, when T cells are restimulated and analyzed at later time points (10 to 14 days) we find a refinement in cytokine profiles: T cells stimulated in the presence of professional APCs produced the Th1 cytokines IL-2 and IFN-gamma, whereas T cells stimulated in the presence of activated keratinocytes produced only the Th2 cytokine IL-4. The specific ability of keratinocytes to induce a Th2 response seems most closely linked to their absence of IL-12 production, and may be important in the maintenance of peripheral tolerance to self-Ags or in the immune response to exogenous Ags, pathogens, or haptens encountered in skin.
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PMID:Keratinocyte-derived T cell costimulation induces preferential production of IL-2 and IL-4 but not IFN-gamma. 791 Jun 19

The major purpose of this study was to elucidate Th1 [interferon (IFN)-gamma and interleukin (IL)-2] and Th2 (IL-4, IL-5 and IL-6) cytokine-producing CD3+ T cells in salivary glands, which are the major mucosal effector tissues in the oral region. Thus, CD3+ T cells were isolated from salivary gland-associated tissues (SGAT) which consist of the submandibular gland (SMG: approximately 46%), the periglandular lymph node (PGLN: approximately 72%), and the cervical lymph node (CLN: approximately 90%). When SMG CD3+ T cells were examined by Th1 and Th2 cytokine-specific ELISPOT and reverse transcriptase-polymerase chain reaction assay, high levels of both cytokine-specific spot-forming cells (SFC) and mRNA for IFN-gamma, and for IL-5 and IL-6 were noted as representative Th1 or Th2 cytokines, respectively. Following stimulation with concanavalin A (Con A), SMG CD3+ T cells expressed mRNA and produced lymphokines for an array of Th1 (IFN-gamma and IL-2) and Th2 (IL-4, IL-5 and IL-6) cytokines. In comparison to the SMG CD3+ T cells, PGLN and CLN contain lower numbers of IFN-gamma-, IL-5 and IL-6-producing T cells. When these two tissues were compared, PGLN CD3+ T cells contained higher numbers of cytokine-secreting cells than CLN. Further, IL-2 and IL-4 SFC and mRNA were also noted in addition to IFN-gamma, IL-5 and IL-6 after Con A activation. These findings showed that CD3+ T cells in SGAT, especially the SMG, are programmed to produce IFN-gamma, and IL-5 and IL-6 as Th1 and Th2 cytokines, respectively in vivo, although these cells are capable of producing other Th1 and Th2 cytokines after receiving appropriate T cell activation signals.
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PMID:Characterization of cytokine-producing cells in mucosal effector sites: CD3+ T cells of Th1 and Th2 type in salivary gland-associated tissues. 795 57

We have shown that gamma delta T cells in human gingiva have an intraepithelial location and, that in the chronic inflammatory disease periodontitis, the expression of CD45RO and CD8 or CD4 is induced on gamma delta T cells. To study the role of gamma delta T cells in local antibacterial responses, we determined the cytokine profiles of isolated human gingival cells. Different T cell subpopulations, isolated by positive selection with mAb-coated magnetic beads and macrophages, as well as epithelial cells, were analyzed for expression of mRNA for 15 cytokines by reverse transcriptase-PCR. The ultrastructure of gingival gamma delta T cells was also studied. The gamma delta T cells expressed mRNA for IFN-gamma, TNF-alpha, TGF-beta 1, and IL-6. Expression of IFN-gamma was a consequence of inflammation. CD4+ gamma delta T cells expressed IFN-gamma only, whereas CD8+ gamma delta T cells expressed all four cytokines. CD8+ cells expressing IFN-gamma, TNF-alpha, and IL-6 in combination suggest a cytotoxic effector function. Gingival gamma delta T cells contained cytoplasmic electron-dense membrane-bound granules and multivesicular bodies that are ultrastructural characteristics of cytotoxic cells. Epithelial cells from inflamed gingiva expressed HLA-DR, CD1a, CD1c, and heat shock protein 60 on the cell surface. They also expressed mRNA for IL-1 beta, IL-6, IL-8, TNF-alpha, and TGF-beta 1. Thus, epithelial cells may function as accessory cells in immune activation and, at the same time, be target cells for CD8+ gamma delta T cells reactive with CD1 Ag or heat shock protein. These results suggest that gamma delta T cells constitute a first line of defense in gingiva, preventing entrance of pathogens by cytotoxicity against infected and stressed epithelial cells, and by control of epithelial cell growth through secretion of regulatory cytokines.
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PMID:Cytokine profile and ultrastructure of intraepithelial gamma delta T cells in chronically inflamed human gingiva suggest a cytotoxic effector function. 805 26

Efficient immunologic tolerance, defined as antigen-specific unresponsiveness, can be peripherally induced by the i.v. injection of syngeneic splenocytes coupled with antigen using ethylene carbodiimide (ECDI). We have previously reported that unresponsiveness induced via i.v. injection of syngeneic splenocytes coupled with intact, UV-inactivated Theiler's murine encephalomyelitis virus (TMEV-SP) resulted in 'split tolerance'. Both virus-specific delayed-type hypersensitivity and IgG2a levels were inhibited, whereas IgG1 levels were increased when compared with sham tolerized controls. In the present report we demonstrate that tolerance induced by i.v. injection of TMEV-coupled splenocytes resulted in antigen-specific inhibition of T cell proliferation, as well as IL-2 and IFN-gamma production in response to both whole TMEV and the immunodominant viral epitope. Additionally, tolerance induction resulted in abrogation of Th1-derived [IL-2, IFN-gamma and LT/tumor necrosis factor-beta (TNF-beta)] cytokine mRNA expression in response to in vitro stimulation with UV-inactivated TMEV as determined by reverse transcriptase polymerase chain reaction. In contrast, expression of Th2-derived (IL-4, IL-6 and IL-10) cytokine mRNA was not affected in tolerized mice. Tolerance functioned directly at the level of CD4+ Th1 cells at both the induction and effector limbs as depletion of CD8+ T cells both prior to in vivo tolerization or in vitro culture had no effect on inhibition of Th1-specific responses. The mechanism of in vivo tolerance induction appeared to be anergy of CD4+ Th1 cells since IL-2, IFN-gamma and LT/TNF-beta mRNA expression as well as virus-specific proliferative responses could be restored by addition of rIL-2 to in vitro cultures of tolerant, CD4+ Th1 populations. These results suggest that in vivo 'split tolerance' induced by i.v. injection of ECDI-fixed, antigen-coupled splenocytes involves anergy of TMEV-specific, CD4+ Th1 lymphocytes and concomitant priming of Th2 cells. The induction of antigen-specific, in vivo anergy has important implications in the design of therapeutic strategies for immunopathologic diseases mediated by Th1 lymphocytes, especially T cell-mediated autoimmune disorders.
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PMID:Anergy in vivo: down-regulation of antigen-specific CD4+ Th1 but not Th2 cytokine responses. 808 Aug 42

Monocytes treated with 500 IU/ml human recombinant interferon-gamma (rIFN-gamma) 1 day before and continuously after human immunodeficiency virus (HIV) infection showed no evidence of virus replication 7 days after addition of the viral inoculum. There was no HIV-associated cytopathic effect, no reverse transcriptase (RT) activity or p24 detected in culture fluids, and no HIV RNA or DNA in cell lysates. Furthermore, no evidence of HIV infection was evident in replicate cultures in which all IFN-gamma was removed at 7 days and the cells were cultured for an additional 3 weeks without IFN-gamma. The 50% inhibitory dose for reduction of maximum RT activity in HIV-infected monocyte cultures was about 1 IU/ml IFN-gamma. No increase in HIV replication was evident in monocytes treated with IFN-gamma at any concentration (0 to 5000 IU/ml) or at any time (7 days before to 10 days after HIV infection). In side-by-side experiments with identical monocytes and HIV-1 stock, rIFN-gamma was 10 to 20 times more effective than rIFN-alpha 2b for induction of antiviral activity. With both interferons, significant antiviral activity was evident with monocytes treated 1 day before, at the time of, or up to 3 days after infection. At 7 to 10 days after infection (a time at which less than 20% of total cells were infected with HIV) addition of even high concentrations of IFN-alpha or IFN-gamma had no effect on virus replication. These data suggest that the principal action of IFN-alpha and IFN-gamma was directed against the fluid-phase virus. Cell-cell spread of infection within the HIV-infected monocyte culture and extent of virus replication in HIV-infected cells were not affected by interferon treatment.
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PMID:Interferon-gamma protects primary monocytes against infection with human immunodeficiency virus type 1. 808 9


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