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)

Clones of human B lymphocytes, obtained after immortalization with Epstein-Barr virus (EBV) of single CD19+ B cells and expansion in the absence of human T lymphocytes, produced mRNA for the T cell cytokines interleukin(IL)-2, IL-4, and interferon (IFN)-gamma. As detected by reverse transcriptase-polymerase chain reaction, IL-2 mRNA was expressed only after stimulation with the combination of phorbol 12-myristate 13-acetate (PMA) plus ionomycin. IL-4 mRNA was constitutively detectable in all (10/10) EBV-transformed B cell clones, and the mRNA for IFN-gamma was constitutively present in half of the clones. In contrast to IL-2 mRNA, the expression of IL-4 and IFN-gamma mRNA could be increased by PMA alone. Most of the clones produced IL-2 bioactivity and immunoreactive protein, but neither IL-4 nor IFN-gamma protein secretion was detected. The intriguing question raised by these results is whether IL-2 secretion could contribute to the immune control of EBV-infected B lymphocytes by cytolytic T cells, and whether normal B lymphocytes can potentially be induced to express certain cytokines including IL-4 in response to the appropriate activation signals.
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PMID:Differential induction of T cell cytokine mRNA in Epstein-Barr virus-transformed B cell clones: constitutive and inducible expression of interleukin-4 mRNA. 838 61

The immunological mechanisms involved in maintenance of an asymptomatic microfilaremic state (MF) in patients with lymphatic filariasis remain undefined. MF patients have impaired filarial antigen (Ag)-specific lymphocyte proliferation and decreased frequencies (Fo) of Ag-specific T cells, and yet elevated serum IgE and antifilarial IgG4. To investigate the mechanism of Ag-specific anergy in MF patients in contrast to amicrofilaremic individuals with chronic lymphatic obstruction (CP), the Fo of Ag-specific lymphocytes from peripheral blood mononuclear cells secreting either IL-4 or IFN-gamma were assessed by filter spot enzyme-linked immunosorbent assay, and IL-10 and transforming growth factor-beta (TGF-beta) mRNA transcript levels were assessed by a semiquantitative reverse transcriptase polymerase chain reaction technique. The Fo of filaria-specific IL-4-secreting lymphocytes were equivalent in both MF (geometric mean [GM] = 1:11,700) and CP (GM = 1:29,300 P = 0.08), whereas the Fo of IFN-gamma-secreting lymphocytes were lower in MF (GM = 1:39,300) than in CP (GM = 1:4,200, P < 0.01). When the ratio of IL-4/IFN-gamma (T helper type 2 [Th2]/Th1)-secreting cells was examined, MF subjects showed a predominant Th2 response (8:1) compared with a Th1 response in CP individuals (1:4). mRNA transcript levels of IL-10 were also significantly elevated in MF compared with CP individuals (P < 0.01). Further, IL-10 and TGF-beta were shown to have a role in modulating the Ag-specific anergy among MF subjects, in that neutralizing anti-IL-10 or anti-TGF-beta significantly enhanced lymphocyte proliferation response (by 220-1,300%) to filarial Ags in MF individuals. These findings demonstrate that MF subjects respond to parasite antigen by producing a set of suppressive cytokines that may facilitate persistence of the parasite within humans while producing little clinical disease.
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PMID:Cytokine control of parasite-specific anergy in human lymphatic filariasis. Preferential induction of a regulatory T helper type 2 lymphocyte subset. 840 19

The immune response that is characteristic of parasitic helminth infections includes components associated with immediate-type hypersensitivity: elevated serum IgE, eosinophilia, and intestinal mast cell hyperplasia. In infection with the parasitic nematode, Heligmosomoides polygyrus, IL-4 mediates protective immunity, suggesting the presence of a host-protective Th2 response. In this investigation, we examined early stages of immune responsiveness to H. polygyrus infection to determine whether and at what stage a specific Th2-like pattern first appears. Using a quantitative reverse transcriptase-polymerase chain reaction assay, we analyzed changes in IL-2, IFN-gamma, IL-3, IL-4, IL-5, IL-6, IL-9, and IL-10 gene expression in the spleen, mesenteric lymph node, and Peyer's patch at various time points after infection. Our results demonstrate a highly specific and reproducible pattern of cytokine gene expression that remains localized to the enteric region. By 6 h after infection, IL-5 and IL-9 mRNA were elevated in the Peyer's patch and IL-3 was elevated by 12 to 24 h after infection. IL-4 RNA became elevated by 4 to 6 days after infection, but little change was observed in IFN-gamma, IL-2, or IL-10 mRNA levels. The early increases in IL-3, IL-5, and IL-9 gene expression after infection were probably T cell-independent, inasmuch as they were observed in Peyer's patches of congenitally athymic mice and anti-CD4, anti-CD8 mAb-treated conventional mice. However, treatment with these mAb considerably decreased cytokine gene expression 6 days after infection, and 8 days after infection, increased IL-4 gene expression in mesenteric lymph node cells was restricted to the CD4+ population. Thus, H. polygyrus infection induces cytokine gene expression that is restricted to some Th2-associated cytokines, is initiated by a T-independent response, and culminates in a T-dependent response.
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PMID:A primary intestinal helminthic infection rapidly induces a gut-associated elevation of Th2-associated cytokines and IL-3. 846 81

We have recently demonstrated that the superantigen staphylococcal enterotoxin A (SEA) conjugated to colon-carcinoma-reactive monoclonal antibodies (MAbs) directs T cells to lyse human colon-carcinoma cells, representing a potential novel tumor therapy. To further analyze the mechanism of antitumor effects of superantigen-activated T cells, we compared the activity of free and MAb-conjugated SEA in a long term in vitro co-culture assay of human peripheral-blood mononuclear cells (PBMC) and colon-carcinoma cell lines. Activation of resting T lymphocytes with SEA conjugated to the colon-carcinoma-reactive MAb C215 or free SEA resulted in strong inhibition of the growth of all studied colon-carcinoma cell lines. The growth of WiDr colon-carcinoma cells was unaffected by the presence of unactivated mononuclear cells, whereas addition of pM concentrations of SEA or C215-SEA conjugate completely suppressed tumor-cell growth. The suppressive effect was mediated by both CD4+ and CD8+ T cells and required the presence of MHC-Class II+ monocytes. The inhibition of tumor-cell growth was to a large extent mediated by soluble factors present in supernatants from SEA- or C215-SEA-activated mononuclear cells. Quantitation of cytokine mRNA in SEA-activated mononuclear cells by the reverse transcriptase-polymerase chain reaction (RT-PCR) revealed strong induction of mRNA encoding the cytokines IL-1 alpha, IL-1 beta, IL-2, IL-6, TNF-alpha, TNF-beta and IFN-gamma. The use of cytokine-specific MAb demonstrated that IFN-gamma was of major importance for the tumor-growth-inhibitory activity in supernatants of SEA-activated lymphocytes. Addition of recombinant cytokines to WiDr colon-carcinoma cells showed that TNF-alpha was able to act synergistically with IFN-gamma to suppress tumor-cell growth. The local production of tumor-suppressive cytokines induced by MAb-targeted superantigens is likely to be of particular relevance for inhibition of the growth of tumor cells not expressing the targeted tumor-associated antigen.
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PMID:Superantigen-induced cytokines suppress growth of human colon-carcinoma cells. 850 23

After vaccination with tetanus toxoid (TT), TT-specific immune responses in humans infected with Schistosoma mansoni were assessed. Peripheral blood mononuclear cells (PBMC) from vaccinated infected subjects and vaccinated uninfected controls were evaluated for their ability to produce cytokines characteristic of Th1 or Th2 cells (interferon [IFN]-gamma or interleukin [IL]-4, respectively) after in vitro restimulation with TT. TT-specific IFN-gamma production by PBMC from infected subjects was inversely related to infection intensity and was significantly lower than TT-specific IFN-gamma production by control PBMC. PBMC from all of the infected subjects and 3 of the 5 controls analyzed by reverse transcriptase-polymerase chain reaction transcribed the IL-4 gene in response to TT restimulation. Together, these results suggest that S. mansoni-infected persons mount a Th2-like response to the bystander antigen TT, while uninfected persons mount a Th1- or Th0-like response.
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PMID:Impairment of tetanus toxoid-specific Th1-like immune responses in humans infected with Schistosoma mansoni. 853 75

IL-15 is a recently described cytokine which resembles IL-2 in its biologic activities, stimulating T cell and NK cell proliferation and activation as well as enhancing B cell expansion and Ab production. Unlike IL-2, IL-15 is not produced by lymphocytes, but instead (at least among cells of the immune system) appears to be synthesized primarily by monocyte/macrophages. We have examined the induction of IL-15 in murine macrophages (by semiquantitative reverse transcriptase-PCR and bioassay) in response to a variety of different macrophage-activating stimuli and compared the regulation of IL-15 production to that of IL-12 and TNF-alpha. Optimal induction of IL-15, in each of the macrophages populations tested, was found to require both priming (IFN-gamma) and triggering (LPS, mycobacteria, or Toxoplasma gondii) stimuli. When compared with IL-12 mRNA synthesis by the same macrophages, IL-15.mRNA production was more resistant to inhibition by the down-regulatory cytokines IL-14, IL-13, and TGF-beta. Moreover, IL-10, which is inhibitory for most other monokines, increased levels of IL-15 mRNA found after stimulation. These data establish IL-15 as a product of the macrophage/monocyte lineage, which is up-regulated on activation. IL-15 could thus play an important role in the initiation of immune responses by microbial agents.
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PMID:Induction and regulation of IL-15 expression in murine macrophages. 854 27

We have assessed regulatory Th cell and cytokine responses in mice after oral immunization with recombinant Salmonella (BRD 847) expressing fragment C of tetanus toxoid, since little information is available to explain how these vectors induce mucosal IgA responses. A single dose of BRD 847 elicited serum IgG2a and mucosal IgA anti-tetanus toxoid Ab responses. To assess Th1-and Th2-type responses, CD4+ T cells from Peyer's patches and spleen were restimulated in vitro, and cytokine-specific ELISPOT, ELISA, and reverse transcriptase-PCR assays were used to assess cytokine patterns. CD4+ T cells produced IFN-gamma and IL-2 as well as IL-10, but not IL-4 or IL-5. Although IL-6 was elevated, further purification of cells from in vitro cultures into CD4+ Mac-1- T cells and Mac-1+ CD4- cells revealed that only the latter cell population had consistently elevated IL-6 gene expression, whereas both sorted populations exhibited increased IFN-gamma and IL-10 gene expression. Thus, orally administered recombinant Salmonella expressing fragment C of tetanus toxoid elicited dominant Ag-specific Th1-type responses together with Th2-type cells producing IL-10 in both mucosal and systemic tissues. Macrophages producing IL-6 were also evident. Our results are consistent with the suggestion that Ag-specific Th1 cells and their derived cytokines, IFN-gamma and IL-2, and Th2-derived IL-10 together with IL-6 produced by macrophages provide important signals for the development of mucosal IgA and serum IgG subclass responses in the absence of preferential expression of Th2 cytokines IL-4 and IL-5.
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PMID:Regulation of mucosal and systemic antibody responses by T helper cell subsets, macrophages, and derived cytokines following oral immunization with live recombinant Salmonella. 856 54

Mice irradiated with UVB, unlike nonirradiated mice, are highly susceptible to syngeneic, immunogenic tumors induced by UVB irradiation or by chemicals. We postulated that UV induced susceptibility to immunogenic tumors results from a reduction in host capacity to generate an interferon (IFN)-gamma immune response to tumor antigens. Shaved BALB/c mice were exposed to 6 x 10(5) J m-2 of UVB radiation delivered intermittently over 12 weeks. The UVB-irradiated and nonirradiated mice received intradermal injections of UVM12 or BP2 tumor cells. After 0, 1.5, 3, 7 or 21 days, draining lymph nodes were excised. Lymph node cells were incubated with UVM12 or BP2 cells that had received 2.5 Gy of gamma-radiation. After 48 h in culture, supernatants were analyzed for IFN-gamma content by enzyme-linked immunosorbent assay and cellular RNA was extracted for mRNA detection by reverse transcriptase-polymerase chain reaction analysis. At 7 days after tumor injection, draining lymph node cells from nonirradiated control mice secreted significant levels of IFN-gamma and contained at least 0.0729 amol of IFN-gamma mRNA/microgram cDNA upon in vitro exposure to gamma-irradiated tumor cells. Draining lymph node cells removed from UV-irradiated mice contained only 18% as much IFN-gamma mRNA and secreted little or no IFN-gamma when exposed to gamma-irradiated tumor cells. A single injection of antibody directed against murine IFN-gamma rendered normal mice as susceptible as UV-irradiated mice to BP2 tumor cells. Thus, chronic UV irradiation leads to an inability of host tumor draining lymph node cells to mount an IFN-gamma response to tumor antigens.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Reduction of interferon-gamma as a critical mechanism by which ultraviolet radiation prevents tumor rejection. 857 Jul 24

During the process of placental implantation, sessile villous trophoblast cells migrate from the villi into the decidua as isolated motile extravillous trophoblast cells. There is differential expression of the epidermal growth factor-receptor (EGF-R) and c-erbB2 proteins on villous and extravillous trophoblast populations. Using monoclonal antibodies to EGF-R and c-erbB2, we have obtained highly purified populations of villous and extravillous trophoblast by fluorescence activated cell sorting. These cells were examined by the reverse transcriptase-polymerase chain reaction (RT-PCR) using nested internal primer pairs for the following cytokines: CSF-1, GM-CSF, TNF-alpha, TGF-beta1, IFN-gamma, IL-2, LIF and also for LIF-receptor. TNF-alpha and TGF-beta 1 were present in all trophoblast populations. GM-CSF and CSF-1 were only found in some samples, with preferential expression of CSF-1 in villous populations. IFN-gamma, IL-2 and LIF mRNA were not found, although all samples contained LIF-receptor mRNA. These cytokines (CSF-1, TGF-beta, TNF-alpha and GM-CSF) are likely to influence trophoblast growth and differentiation in an autocrine manner, since their receptors are also present on trophoblast. These results illustrate a quick and simple method to analyse for the presence of cytokine and other transcripts in trophoblast subpopulations during early pregnancy.
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PMID:Screening for cytokine mRNA in human villous and extravillous trophoblasts using the reverse-transcriptase polymerase chain reaction (RT-PCR). 858 67

In murine contact photosensitivity, a cutaneous delayed-type hypersensitivity reaction, preirradiation of the photosensitization site with UVB induced Ag-specific, afferent limb-acting, CD4+CD8- suppressor T cells (Ts). The present study examined usage of TCR V beta and production of immunosuppressive cytokines in Ts propagated in vitro. Spleen cells from UVB-preirradiated, 3,3',4',5- tetracholorosalicylanilide (TCSA)-photosensitized mice were stimulated with 3000-rad-irradiated lymph node cells (LNC) from TCSA/UVA-sensitized mice (LNCTCSA) in the presence of rIL-t. After several rounds of antigenic stimulation, a T cell line (B+TCL) consisted exclusively of CD3+CD4+CD8- V beta 7+ and V beta 13+ populations. Transfer to naive recipients of B+TCL treated with anti-V beta mAb plus complement revealed that the V beta 7+ cells suppressed both the in vivo and the in vitro aspects of contact photosensitivity to TCSA in an Ag-specific manner. The in vitro suppressive activity of B+TCL was neutralized by anti-IL-10 mAb, but not by anti-IL-4 mAb, indicating a crucial role of IL-10 in UBV-induced suppression. Upon stimulation with 3000-rad-irradiated-LNCTCSA, B+TCL released IL-4 and IL-10 but not IL-2, and V beta 7+ cells produced IL-10. The reverse transcriptase-PCR detected mRNA for IL-4 and IL-10 but not that for IL-2, IFN-gamma, or TGF-beta in B+TCL stimulated with or without concanavalin A. In accordance with the findings in B+TCL, spleen cells from UVB preirradiation plus TCSA/UVA mice contained V beta 7+ T cells that suppressed contact photosensitivity to TCSA and produced substantial amounts of IL-4 that provided a microenvironment for Th2 cell generation. We conclude that UVB preirradiation and photosensitization result in the generation of V beta 7+ Th2 cells that suppress contact photosensitivity by releasing IL-10. The dysfunction of effector Th1 cells underlying UVB suppression of delayed-type hypersensitivity seems to be due not only to altered APC function but also to counteraction of Th2 cells by Th1 cells.
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PMID:TCRV beta 7+ Th2 cells mediate UVB-induced suppression of murine contact photosensitivity by releasing IL-10. 859 33


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