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)

The effect of IgA from human immunodeficiency virus type 1 (HIV-1)-infected patients on infection of primary human blood monocytes with the monocyte-tropic strain HIV-1Bal was evaluated in vitro. Preincubation of HIV-1Bal with purified serum IgA from 6 of 14 patients but from none of 5 seronegative subjects caused a > 50% increase in reverse transcriptase activity. This increase was inhibited by preincubation of monocytes with nonimmune IgA, suggesting a role for Fc alpha receptors. Results were independent of CD4 T cell number and clinical stage. The IgA-mediated enhancement extended to more biologically relevant human mononuclear cells isolated from the intestinal lamina propria. The ability of serum IgA to enhance HIV-1 infection may be relevant to infection of both circulating monocytes and mucosal macrophages. These studies suggest the need to characterize the complex contribution of IgA and the mucosal immune system in promoting and preventing primary HIV-1 infection.
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PMID:Modulation of human immunodeficiency virus type 1 infection of human monocytes by IgA. 765 82

We have used the potent mucosal immunogen cholera toxin (CT) to assess antigen-specific CD4+ T-cell responses, including Th1- and Th2-type cells in mucosa-associated tissues, e.g. Peyer's patches (PP), and systemic tissue, e.g. spleen (SP), for their regulatory role in the induction of CT-specific B-cell antibody responses in the gastrointestinal (GI) tract as well as in systemic sites. The CT was given by either oral or intravenous (i.v.) routes and the mice orally immunized with CT exhibited brisk IgA anti-CT antibody responses in faecal extracts and elevated IgG anti-CT antibody responses in serum. Further, significant IgA anti-CT spot-forming cells (SFCs) were seen in lamina propria lymphocytes (LPLs) from mice orally immunized with CT. In contrast, i.v. immunization with CT induced IgM and IgG anti-CT SFC responses in SP, and serum anti-CT antibodies of these two isotypes; no anti-CT responses were induced in the GI tract after immunization by this route. The CD4+ T cells isolated from PP and SP of mice orally immunized with CT were stimulated in vitro with CT-B-coated latex microspheres for 1-6 days, and the induction of IL-2 and interferon gamma (IFN-gamma) (Th1-type) or IL-4 and IL-5 (Th2-type) producing SFCs were analysed by a cytokine-specific ELISPOT and cytokine-specific mRNA was detected by reverse transcriptase (RT)-PCR assays.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Helper Th1 and Th2 cell responses following mucosal or systemic immunization with cholera toxin. 797 32

Aberrant elevation of serum IgA and induction of murine IgA nephropathy following dietary exposure to the naturally occurring trichothecene vomitoxin (VT or deoxynivalenol) may involve dysregulation of cytokine production at the T cell level. EL4.IL-2 (EL-4), a cloned thymoma that produces interleukins (IL)-2, 4, 5, and 6, was used as a T cell model to investigate the in vitro effects of VT on interleukin production and gene expression. When supernatants of cells stimulated with phorbol 12-myristate 13-acetate (PMA) were assessed by enzyme-linked immunosorbent assay, IL-2, 4, and 5 were increased in the presence of 50 and/or 100 ng/ml VT for 2 and/or 8 days of culture. IL-2, 5, and 6 were also significantly elevated in the presence of 10-100 ng/ml of cycloheximide (CHX), another protein synthesis inhibitor, after 8 days of culture. As demonstrated by Northern analysis, VT at the levels between 50 and 100 ng/ml superinduced IL-2, 4, 5, and 6 mRNAs in PMA-stimulated EL-4 cells during a 24 hr culture period. Similar effects in PMA-treated samples were observed for CHX at 50, 100, 250, 1000, and 10000 ng/ml. mRNA levels for both IL-4 and IL-5, but not IL-2 and IL-6, were increased in unstimulated EL-4 cultures exposed to 50 and 100 ng/ml VT for 48 hr when analyzed by reverse transcriptase-polymerase chain reaction. Using [3H]leucine incorporation as a measurement of protein synthesis, IC50s for VT and CHX were estimated to be 280 and 55 ng/ml, respectively. This study indicates that VT as well as CHX could increase production of several interleukins in the EL-4 model even when present at concentrations that partially inhibited protein synthesis, whereas IL mRNA superinduction occurred across a broader range of concentrations that included maximal protein synthesis inhibition.
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PMID:Elevated gene expression and production of interleukins 2, 4, 5, and 6 during exposure to vomitoxin (deoxynivalenol) and cycloheximide in the EL-4 thymoma. 804 72

Serum specimens from 66 HIV-1-infected subjects were tested by ELISA for the presence of IgA antibodies to HIV-1: 44 samples were found positive and 37 were confirmed by immunoblot. In these subjects, the presence of anti-HIV IgA antibodies was studied in relation to the total count of circulating CD4+ lymphocytes and to the level of serum IgA. A significative correlation (P < 0.03) was found between the absence of IgA to the subunit p68 of the reverse transcriptase and a count of CD4+ cell < 400/mm3 or total IgA level over 4.25 g/l. The same pattern was observed for the IgA antibodies to the p52 subunit but the association was just not significant (P < 0.07). No significant decrease was noted for the IgA directed towards the other proteins of HIV-1, especially the products of the gag gene.
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PMID:Prognostic value of serum immunoglobulin A antibodies to pol gene products during HIV-1 infection. 809 40

Antibody to hepatitis C as measured by the ELISA method is common in alcoholics. The presence of antibody to C 100-3 has been associated with more advanced disease. However, few studies have investigated the clinical significance of hepatitis C infection as defined by the presence of circulating viral RNA in alcoholics. We have prospectively examined 48 consecutive alcoholic patients for the presence of antibody to hepatitis C by an ELISA for antibody to the C100-3 antigen and by the reverse transcriptase polymerase chain reaction (PCR) using nested primers for the 5' nontranslated region of the viral RNA. Patients with liver disease were scored for disease severity by the combined clinical and laboratory index (CCLI). Overall, 12 of 48 patients (25%) were ELISA positive and eight of 48 (16%) were PCR positive. Among the 34 patients with liver disease, 10 (29%) were ELISA positive and six (18%) were PCR positive. All PCR-positive patients were also ELISA positive. There was no significant difference in the disease severity score (CCLI) or the duration of clinical disease in PCR-positive versus PCR-negative patients with liver disease. However, PCR-positive patients were significantly younger (43 +/- 6 vs. 55 +/- 10 yr, p = 0.001), indicating an earlier onset of severe disease in PCR-positive patients. There were no false-negative ELISA tests in either those with or those without liver disease. Among the 34 patients with liver disease, four of 10 patients with positive antibody were negative by PCR. Neither individual immunoglobulin levels (IgG, IgM, IgA) nor total globulins were significantly different between the ELISA-positive/PCR-negative patients and ELISA-positive/PCR-positive patients. When the entire group of 34 patients with liver disease was considered, we could not detect a significant correlation between ELISA absorbance and total globulins, and only a weak correlation between absorbance and immunoglobulin G (p = 0.49). These data show that the majority of alcoholic patients with liver disease and positive antibody to hepatitis C also have demonstrable viremia by PCR, and may require further evaluation and treatment. Elevated immunoglobulins in these patients do not correlate strongly with ELISA absorbance for anti-HCV. The presence of clinically advanced disease at a significantly younger age in the PCR-positive group is consistent with the concept of synergy between active viral infection and alcohol abuse in the development of liver disease in alcoholic patients.
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PMID:Hepatitis C infection by polymerase chain reaction in alcoholics: false-positive ELISA results and the influence of infection on a clinical prognostic score. 831 32

In vitro experiments have suggested that interleukin (IL)-6 may contribute to human immunodeficiency virus (HIV) burden and to immunological abnormalities in HIV-infected patients. We had the opportunity to directly address this question in vivo through the virological and immunological monitoring of HIV-infected patients treated with an anti-IL-6 monoclonal antibody (mAb) for a lymphoma (ANRS 018 trial). Sixteen courses of anti-IL-6 mAb administration, performed in 11 patients, were studied. All patients were at a late stage of HIV infection. The HIV load and the immunological status were determined at the initiation of each course and at its end, 21 days later. The mAb induced no significant change of HIV load, as evaluated by p24 antigenemia, plasma viremia, and quantification of circulating HIV RNA by reverse transcriptase-polymerase chain reaction and branched DNA techniques. The anti-IL-6 mAb also did not affect CD4+, CD8+, and CD19+ circulating cell counts, nor the serum concentrations of sIL-2R and of sCD8. In contrast, the mAb completely abrogated acute-phase reaction, as demonstrated by the normalization of C-reactive protein and fibrinogen circulating levels (p = 0.013 and p = 0.008, respectively). It increased serum albumin concentration. The latter effect was restricted to patients with a spontaneously low albuminemia (p = 0.01). It decreased B-lymphocyte hyperactivity, as reflected by decreased IgG and IgA serum levels (p = 0.008 and p < 0.001, respectively), and by a decreased production of IgG in vitro (p = 0.017). In contrast, the IgM hyperproduction was not affected by the mAb. Therefore, increased IL-6 production in HIV-infected patients at a late stage of the infection may not stimulate HIV replication in vivo, but it may represent a key mechanism contributing to the metabolic and immunological dysbalance of the disease.
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PMID:In vivo role of IL-6 on the viral load and on immunological abnormalities of HIV-infected patients. 852 34

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

In this study, we have investigated CD40 expression in human peripheral blood eosinophils and in human chronically inflamed nasal tissues, i.e., nasal polyps. We show by both reverse transcriptase-PCR and Northern blot analysis that eosinophils from allergic subjects express human CD40 mRNA. We also show that constitutive CD40 mRNA expression in eosinophils could be upregulated by exposure to IgA immune complexes and downregulated by IL-10 and the synthetic steroid budesonide. In addition, we demonstrate that eosinophils express CD40 protein by flow cytometry. Such expression is biologically functional as cross-linking CD40 with CD40 mAbs enhances eosinophil survival in a dose-dependent fashion; in addition, CD40 ligation stimulates eosinophils to release GM-CSF. CD40-mediated eosinophil survival was largely inhibited by an anti-GM-CSF neutralizing antibody suggesting GM-CSF involvement in the survival enhancing mechanism. CD40 mRNA was also detected in total RNA extracted from nasal polyp tissues but not in RNA isolated from normal nasal mucosa (inferior turbinate); by immunohistochemistry, we were able to detect immunoreactive CD40 protein in a variety of cell types in the polyp stroma, but primarily in eosinophils. These observations suggest previously unforeseen interactions between eosinophils and cells expressing the CD40 ligand and, thus, novel pathways by which eosinophils may contribute to the regulation of airway inflammation.
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PMID:CD40 expression by human peripheral blood eosinophils. 860 42

Using a degenerate oligonucleotide primer specific for immunoglobulin (Ig) constant type 1 (C-1 set) domain genes, products were amplified by the reverse transcriptase-polymerase chain reaction from nurse shark spleen cDNA. The deduced protein sequence of one of these clones reveals a novel Ig class in cartilaginous fish. A complete mRNA could encode a mature protein bearing an amino-terminal variable (V) domain, followed by six C-1 set domains, and ending in a carboxy-terminal tail typical of secreted IgM, IgA, and the new antigen receptor (NAR). The two amino-terminal C domains are orthologous to IgX (or IgR), an Ig heavy (H) chain class in the skate, and the last four domains are homologous to the carboxy-terminal four domains of NAR. We designate this "chimeric" Ig class IgNARC for Ig new antigen receptor from cartilaginous fish. Like NAR, but unlike shark IgM, IgNARC is encoded by very few V and C genes which apparently are not closely linked. The number of bands that hybridize with exon-specific probes varies with genomic DNA from individual sharks, suggestive of different numbers of IgNARC genes in different animals. A protein of approximately 95 kDa, which is likely to be the IgNARC H chain, is immunoprecipitated with both light chain-specific monoclonal antibodies and with antisera generated to a peptide comprising the IgNARC carboxy-terminal tail. We conclude that the arsenal of secreted antigen receptors in cartilaginous fish is greater than previously believed. In addition, our data cast doubt on the dogma that IgM is the primordial Ig isotype.
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PMID:A novel "chimeric" antibody class in cartilaginous fish: IgM may not be the primordial immunoglobulin. 864 77

Despite the likely role of mucosae in human T cell leukemia virus type I (HTLV-I) transmission, little is known about the mucosal immune response to HTLV-I. The present study evaluated the antibody response to HTLV-I in oral mucosa and the value of crevicular fluid rich saliva (CFRS) for diagnosing HTLV-I infection. CFRS and sera from patients with tropical spastic paraparesis/HTLV-I-associated myelopathy (TSP/HAM), asymptomatic carriers, and HTLV-I seronegative individuals from Tumaco, Colombia, were analyzed for HTLV-I specific IgG, IgA, and secretory IgA (sIgA). Detection of IgG in CFRS by enzyme-linked immunosorbent assay correlated with its presence in sera for TSP/HAM patients and asymptomatic carriers. IgA and sIgA were more frequently detected in CFRS and sera from TSP/HAM patients than in those from asymptomatic carriers. An HTLV-I pol fragment could be amplified from CFRS by reverse transcriptase-PCR in 3 TSP/HAM patients and one asymptomatic carrier, all of whom had an IgA response in CFRS but not in sera. The more frequent detection of IgA and sIgA in sera and CFRS of TSP/HAM patients suggests increased viral replication. Further, the association of viral RNA in CFRS with a local IgA response may signify rounds of viral replication in the oral cavity.
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PMID:Human T-lymphotropic virus type I (HTLV-I)-specific antibodies and cell-free RNA in crevicular fluid-rich saliva from patients with tropical spastic paraparesis/HTLV-I-associated myelopathy. 883 67


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