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 American cutaneous leishmaniasis (ACL), Leishmania parasites enter the epidermis of the host via the bite of infected sandflies. Immune responses against the parasite vary from "effective" in localized (LCL) to a state of "selective anergy" in diffuse (DCL) cutaneous leishmaniasis, whereas the intermediate muco-cutaneous form (MCL) is characterized by an exacerbated cell-mediated immunity. We have shown that in LCL epidermis, Langerhans cells (LC) are increased, HLA-DR is universally expressed and intercellular adhesion molecule-1 (ICAM-1) immunoreactivity is distributed in patches. In addition, mRNA for IL-1 beta, IL-8, TNF alpha, TNF beta, and INF gamma may be detected in epidermal sheets by reverse transcriptase followed by polymerase chain reaction (RT-PCR). In contrast, DCL epidermis shows fewer LC than LCL epidermis, and expression of ICAM-1, HLA-DR, and IL-1 beta mRNA cannot be detected. MCL lesions show a mucosal epithelium lacking LC, but ICAM-1 is universally expressed. The clinical manifestations of ACL can be reproduced experimentally in different strains of inbred mice. In healthy mice, we have shown a positive correlation between LC and dendritic epidermal T cells (DETC) numbers. This correlation was not, however, observed in L. mexicana-infected mice, suggesting that infection alters the balance between the two cell types. In addition, agents that modulate LC and DETC cell densities change the development of experimental leishmaniasis. These results suggest that the epidermis is essential in determining the type of immune response that is developed against the Leishmania parasites.
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PMID:Epidermal compromise in American cutaneous leishmaniasis. 135 84

In the present report, we have studied the in vitro transition of normal blood monocytes to macrophages by changes in cell morphology, and the expression of surface antigens with a panel of monoclonal antibodies. The maturation process was accompanied by notable changes in cell-surface markers in a time-dependent manner. The percentage of cells expressing CD11c, ICAM-1, HLA-DR, and Fc receptor class III increased while the CD4 and CD35 expression was markedly decreased. After demonstrating that in vitro monocytes mature to macrophages in a recognizable manner, we studied the susceptibility to HIV-1 infection at time points representing different stages of cell maturation. The results show that monocyte/macrophages are susceptible to HIV-1 infection at all stages of differentiation. However, the kinetics of virus replication depends on the degree of maturation at the time of infection. Two major patterns of replication were observed: Infection of monocytes resulted in efficient virus production measurable by reverse transcriptase activity in culture supernatant, whereas infection of fully differentiated macrophages yielded low but sustained virus release only demonstrable by p24 antigen assay. We were not able to detect differences in the capacity of the virus to infect and replicate in monocyte/macrophages with respect to cellular origin of the virus isolate and whether the viruses were laboratory-adapted strains or low-passaged patient isolates.
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PMID:In vitro maturation of mononuclear phagocytes and susceptibility to HIV-1 infection. 185 87

Psoriatic skin lesions contain HLA-DR positive T lymphocytes, and other activation antigens, which suggest that the T cells may be producing lymphokines. Gamma interferon is produced by activated T cells, and its presence in psoriasis has been inferred by the lesional keratinocyte expression of 3 gamma interferon-inducible proteins i.e. HLA-DR, intercellular adhesion molecule-1, and gamma-IP-10. To determine whether gamma interferon is being produced directly in psoriatic lesions, punch biopsies of normal and diseased skin were separated into epidermal sheets and dermal fragments. Total cellular RNA was isolated from each epidermal and dermal compartment, and reverse transcribed followed by amplification of the resultant DNA by polymerase chain reaction. The amplification process involved the use of 5' and 3' primers for gamma interferon, and tumor necrosis factor-alpha, with beta-actin serving as a control. Gamma interferon mRNA, but not tumor necrosis factor alpha mRNA, was detectable in 4 of 5 psoriatic epidermal specimens. Neither mRNA was detectable in any normal skin dermal/epidermal specimens. Gamma interferon mRNA was also detectable in a single psoriatic dermal specimen. If reverse transcriptase was omitted, no polymerase chain reaction products were detected, indicating that the fragments detected were not derived from contaminating genomic DNA. These results indicate that gamma interferon mRNA can be extracted and successfully detected from human psoriatic lesional skin biopsies, using polymerase chain reaction technology. This molecular approach can easily be expanded to measure many other cytokines in both epidermal and dermal locations. The detection of gamma interferon in this clinical setting may be of particular pathophysiological significance because injection of gamma interferon has been reported to induce psoriatic lesions.
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PMID:Detection of interferon-gamma mRNA in psoriatic epidermis by polymerase chain reaction. 190 50

A lymphoid cell line CK-a was established from peripheral blood of an infant with acute lymphoblastic leukemia of non-T, non-B cell type with mediastinal tumor. The CK-a cells were positive for surface immunoglobulins, Epstein-Barr virus-specific nuclear antigen, HLA-DR and Leu 12 antigens, and negative for sheep erythrocyte-rosette-receptor, and Leu 1, 2, 3 and 4 antigens. Budding particles were detected in electron micrographs of ultrathin sections of the CK-a cells. In the culture media of CK-a cells, particles with a buoyant density of 1.16 g/ml and labeled with [3H]uridine and [35S]methionine but not with [3H]thymidine were found to carry reverse transcriptase activity which preferred Mg2+ to Mn2+. Enveloped particles of 80 to 120 nm in diameter were detected in the fractions at 1.16 g/ml by electron microscopy. Thus, the particles had properties compatible with a definition of Retroviridae, and were tentatively named CK virus (CKV). The genome size of CKV RNA determined by agarose-acrylamide composite gel electrophoresis was 6.1 +/- 0.2 kb. Immune electroblotting assay detected antibody reactive with a CKV protein with a molecular weight of 67,000 in the serum of the patient, but not in sera of an adult T cell leukemia patient and healthy controls. No syncytia were formed by mixed cultures of CK-a and XC cells.
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PMID:Retrovirus produced by a lymphoid cell line from an infant with acute lymphoblastic leukemia. 288 14

Human retroviruses have recently been linked with T cell lymphoproliferative disorders and with the acquired immune deficiency syndrome. We investigated the mechanisms for acquired pure red cell aplasia and cutaneous anergy in a patient with the chronic T gamma-lymphoproliferative disease (T gamma-LPD) syndrome. Patient marrow erythroid progenitors (BFU-E) were 17 +/- 9% of control and were selectively increased to 88-102% of control after marrow T cell depletion. Patient Leu 2+ suppressor T cells spontaneously produced high titers of human gamma-interferon and resulted in a concentration-dependent selective inhibition (74-91%) of BFU-E when co-cultured with autologous or allogeneic marrow. Conditioned media (CM) derived from patient Leu 2+ T cells similarly inhibited growth of autologous or allogeneic marrow BFU-E. The inhibitory factor derived from patient CM was acid-labile (pH 2) and sensitive to trypsin; prior treatment of patient T cells with anti-HLA-DR monoclonal antibody plus complement abrogated the suppressive effect of T cell-derived CM. Patient peripheral blood mononuclear cells (PBMC) were unable to support growth of cultured interleukin 2 (IL 2)-dependent T cells, but responded to exogenous IL 2 in vitro with a 16-21-fold augmentation, relative to control, in mitogen-induced proliferation. Antibodies to HTLV-I core proteins p19 and p24 but not to HTLV-III proteins were detected in patient serum by Western blotting; patient cultured PBMC stained (7-11%) with antibodies to p19 and p24. Patient cultured PBMC demonstrated integrated HTLV-I genomic sequences by the Southern technique and expressed both specific HTLV-I genomic sequences by RNA dot blot plus reverse transcriptase activity. Utilizing a cloned DNA probe for the beta chain of the T cell receptor gene, patient PMBC demonstrated gene rearrangements providing presumptive evidence for clonality. The presence in serum of HTLV-I p19 and p24 antibodies, the expression of p19 and p24 core antigens on patient mononuclear cells, the evidence of HTLV-I proviral integration sequences and the expression of HTLV-I genomic sequences in patient cells, indicates infection with HTLV-I and raises the possibility of an etiologic link between human retrovirus infection and some instances of large granular lymphocytic leukemia (T gamma-LPD).
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PMID:Human T cell leukemia virus-I-associated T-suppressor cell inhibition of erythropoiesis in a patient with pure red cell aplasia and chronic T gamma-lymphoproliferative disease. 289 60

A new human monoclonal plasma cell line, designated UTMC-2, was established from the pleural effusion of a patient with immunoglobulin (Ig)A kappa-related multiple myeloma. The cultured cells were Epstein-Barr virus-negative and exhibited the morphological and ultrastructural features characteristic of plasma cells. Immunohistochemical analyses revealed the presence of cytoplasmic IgA kappa as well as the plasma cell-associated surface antigens CD38 and CD56. Other B-cell markers, including CD10, CD19, CD20, and HLA-DR, were absent. The UTMC-2 cells were interleukin (IL)-6 responsive: Co-culture with IL-6 increased IgA kappa synthesis and cell proliferation in a dose-dependent manner. In contrast, an IL-6 antisense oligonucleotide had an opposite effect. Although the UTMC-2 cells expressed IL-6 mRNA (as demonstrated by reverse transcriptase-polymerase chain reaction (RT-PCR)) and contained IL-6, the concentration of this cytokine in cell culture supernatants was less than that detectable by the enzyme-linked immunosorbent assay (ELISA) employed (i.e. <3 pg/ml). Further, cell growth was not inhibited by polyclonal or monoclonal anti-IL-6 antibodies. Flow cytometric analysis revealed that IL-6 receptors present on the surface of the UTMC-2 cells were not saturated with endogenous IL-6. Taken together, these results indicate that, in this human plasma cell line, IL-6 functions uniquely in an intracellular autocrine fashion to enhance Ig synthesis and cell growth. In this respect, the UTMC-2 cells represent a novel resource for further study of the role of IL-6 in the pathogenesis of multiple myeloma.
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PMID:Characterization of a novel interleukin-6 autocrine-dependent human plasma cell line. 752 62

The effects of staphylococcal enterotoxin B (SEB), a Staphylococcus aureus-derived bacterial superantigen, on expression of intercellular adhesion molecule-1 (ICAM-1) were examined in cultured normal and transformed (DJM-1 cells) human keratinocytes by flow cytometry, confocal microscopy, digital image processing, and reverse transcriptase-polymerase chain reaction. SEB significantly upregulated ICAM-1 expression in the interferon-gamma (IFN-gamma)-pretreated, HLA-DR-positive normal keratinocytes and DJM-1 cells in a dose-dependent manner, but not in the untreated, HLA-DR-negative cells. Other toxins such as diphtheria and pertussis toxins did not have the effect. The distribution of SEB and HLA-DR molecules was identical on the IFN-gamma-treated, HLA-DR-positive DJM-1 cells by confocal microscopy. Digital image processing analysis demonstrated that SEB induced a transient increase of intracellular calcium concentration only in the IFN-gamma-treated DJM-1 cells. Pretreatment of the IFN-gamma-treated DJM-1 cells with anti-major histocompatibility complex class II monoclonal antibody completely blocked the effect of SEB. Furthermore, ICAM-1 mRNA was detected in the IFN-gamma-pretreated, SEB-exposed normal keratinocytes by reverse transcriptase-polymerase chain reaction. Our results demonstrate that SEB binds to keratinocytes, presumably via major histocompatibility complex class II molecules such as HLA-DR, triggers calcium mobilization, and induces the synthesis of ICAM-1 molecules. We speculate that, in various cutaneous disorders, SEB penetrates the epidermis and interacts with HLA-DR-positive keratinocytes to upregulate ICAM-1 expression, thus modulating the course of the inflammatory process.
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PMID:Staphylococcal enterotoxin B upregulates expression of ICAM-1 molecules on IFN-gamma-treated keratinocytes and keratinocyte cell lines. 756 Nov 55

Two new myeloid cell lines (K051 and K052) were established from a patient with multilineage CD7-positive acute leukemia. The K051 and K052 were established from the patient's bone marrow cells at diagnosis and at relapse, respectively. The K051 cell expressed myeloid-associated antigens (CD13 and CD33), a platelet-associated antigen (CD41), and an erythroid antigen (glycophorin A). The K052 cell expressed myeloid-associated antigens (CD13, CD14, and CD33), lymphoid markers (CD2, CD5, and CD7), and HLA-DR. Chromosome analysis of both cell lines showed a 17p- chromosome. Both cell lines were investigated for aberrations of the p53 gene and the N-ras gene. A p53 mutation detected in both cell lines consisted of a C-->T substitution in codon 248. An N-ras mutation detected only in the K052 cell consisted of a G-->C substitution in codon 13. Expression of the multidrug resistance gene (MDR1) was also investigated by the semiquantitative reverse transcriptase-polymerase chain reaction (RT-PCR). MDR1-mRNA was more highly expressed by the K052 cell than the K051 cell, being equivalent to that in HEL cells. The functional MDR1-protein against vincristine was also observed, and its function was inhibited by verapamile and Cyclosporin A. The K052 cells were capable of phenotypic or morphologic differentiation after being incubated with granulocyte colony-stimulating factor, interleukin-2, phorbol 12-myristate 13-acetate, or 1,25-dihydroxy-vitamin D3. In contrast, the K051 cells responded phenotypically to retinoic acid. Thus, the K051 and K052 cell lines will be useful for investigating the cellular and molecular events in leukemogenesis and differentiation, and the mechanism of expression of the MDR1 gene.
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PMID:p53 and N-ras mutations in two new leukemia cell lines established from a patient with multilineage CD7-positive acute leukemia. 769 50

Major histocompatibility complex (MHC) class II deficiency is an inherited autosomal recessive combined immunodeficiency. The disease is known as bare lymphocyte syndrome (BLS). BLS is characterized by a lack of constitutive MHC class II expression on macrophages and B cells as well as a lack of induced MHC class II expression on cells other than professional antigen-presenting cells (APCs) due to the absence of mRNA and protein of the human leukocyte antigen (HLA) class II molecules, designated HLA-DR, -DQ, and -DP. The defect in gene expression is located at the transcriptional level and affects all class II genes simultaneously. Here we have analyzed transcription and protein expression of class II antigens in Epstein-Barr virus (EBV)-transformed B lymphoblastoid cell lines and mononuclear cells (MNCs) of twin brothers. Whereas flow cytometric analysis failed to detect class II antigens on the cell surface of the patients' EBV-B cells and MNCs, examination of the genes coding for HLA-DR, -DQ, -DP, and the invariant chain (Ii) by reverse transcriptase-polymerase chain reaction amplification resulted in an unusual mRNA pattern in the B cell lines of the patients (HLA-DR alpha +, -DR beta, -DQ alpha +, -DQ beta -, -DP alpha -; -DP beta +, Ii+). In accordance with these findings no HLA-DR beta-specific protein was detected by immunoblotting, whereas low levels of HLA-DR alpha and normal levels of Ii were present. In contrast to EBV-B cells, the MNCs of both patients displayed a residual HLA-DR beta, -DQ beta, and -DP alpha mRNA signal. Furthermore, HLA-DR beta-specific protein was found in addition to HLA-DR alpha by immunoblotting of cell lysates, even though it was clearly decreased as compared with controls. Our results indicate that the defect in class II antigen expression is not necessarily present to the same extent in B cells and cells of other lineages. mRNA levels of HLA-DR beta were found to be enriched in adherent cells within the MNC fraction. Further investigations indicated that the MHC class II expressed is functional in antigen presentation, as the two boys' CD4+ T cells became activated and expressed interleukin-2R after stimulation of peripheral blood mononuclear cell cultures with recall antigen (tetanus toxoid). Furthermore, T cells tested in one of the two patients responded to both MHC class I and II allostimulation, and this response was inhibited by monoclonal antibodies of the respective specificity.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Molecular characterization of major histocompatibility complex class II gene expression and demonstration of antigen-specific T cell response indicate a new phenotype in class II-deficient patients. 769 27

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


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