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: UMLS:C0021051 (immunodeficiency)
71,517 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Recently, gene delivery vectors based on human immunodeficiency virus (HIV) have been developed as an alternative mode of gene delivery. These vectors have a number of advantages, particularly in regard to the ability to infect cells which are not actively dividing. However, the use of vectors based on human immunodeficiency virus raises a number of issues, not the least of which is safety; therefore, further characterization of marking and gene expression in different hematopoietic lineages in primate animal model systems is desirable. We use two animal model systems for gene therapy to test the efficiency of transduction and marking, as well as the safety of these vectors. The first utilizes the rhesus animal model for cytokine-mobilized autologous peripheral blood CD34(+) cell transplantation. The second uses the SCID-human (SCID-hu) thymus/liver chimeric graft animal model useful specifically for human T-lymphoid progenitor cell reconstitution. In the rhesus macaques, detectable levels of vector were observed in granulocytes, lymphocytes, monocytes, and, in one animal with the highest levels of marking, erythrocytes and platelets. In transplanted SCID-hu mice, we directly compared marking and gene expression of the lentivirus vector and a murine leukemia virus-derived vector in thymocytes. Marking was observed at comparable levels, but the lentivirus vector bearing an internal cytomegalovirus promoter expressed less efficiently than did the murine retroviral vector expressed from its own long terminal repeats. In assays for infectious HIV type 1 (HIV-1), no replication-competent HIV-1 was detected in either animal model system. Thus, these results indicate that while lentivirus vectors have no apparent deleterious effects and may have advantages over murine retroviral vectors, further study of the requirements for optimal use are warranted.
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PMID:Marking and gene expression by a lentivirus vector in transplanted human and nonhuman primate CD34(+) cells. 1062 39

Lentiviral vectors have been proposed as a more efficient alternative to Moloney murine leukemia virus-based retroviral vectors for transduction of human hematopoietic progenitors and stem cells. These studies were designed to evaluate the conditions that influence transduction frequency of CD34(+) progenitors, with the goal of optimizing efficiency of stable gene transfer with lentiviral vectors. CD34(+) human cord blood cells and 293 cells were transduced with a human immunodeficiency virus (HIV)-1 derived lentiviral vector pseudotyped with vesicular stomatitis virus glycoprotein and carrying an internal human cytomegalovirus promoter driving enhanced green fluorescent protein (eGFP) expression. Using fluorescence-activated cell sorting analysis of eGFP, we observed pseudotransduction beginning at the time of vector addition and lasting up to 24 h in CD34(+) cells and up to 72 h in 293 cells. Integrase-defective lentiviral vector caused transient eGFP expression for up to 10 days in CD34(+) cells and for up to 14 days in 293 cells. Protamine sulfate conferred no increase in transduction efficiency of CD34(+) cells on fibronectin-coated plates. Transduction frequency was related directly to vector concentration and not to multiplicity of infection across the ranges tested. First- and second-generation lentiviral vectors transduced CD34(+) cells equally, demonstrating a lack of dependence on HIV-1 accessory proteins. These findings will be useful for the optimal utilization of this new class of vectors for transduction of human hematopoietic stem cells.
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PMID:Critical factors influencing stable transduction of human CD34(+) cells with HIV-1-derived lentiviral vectors. 1089 30

Lentivirus-derived vectors are very promising gene delivery systems since they are able to transduce nonproliferating differentiated cells, while murine leukemia virus-based vectors can only transduce cycling cells. Here we report the construction and characterization of highly efficient minimal vectors derived from simian immunodeficiency virus (SIVmac251). High-fidelity PCR amplification of DNA fragments was used to generate a minimal SIV vector formed from a 5' cytomegalovirus early promoter, the 5' viral sequences up to the 5' end of gag required for reverse transcription and packaging, the Rev-responsive element, a gene-expressing cassette, and the 3' long terminal repeat (LTR). Production of SIV vector particles was achieved by transfecting 293T cells with the vector DNA and helper constructs coding for the viral genes and the vesicular stomatitis virus glycoprotein G envelope. These SIV vectors were found to have transducing titers reaching 10(7) transducing units/ml on HeLa cells and to deliver a gene without transfer of helper functions to target cells. The central polypurine tract can be included in the minimal vector, resulting in a two- to threefold increase in the transduction titers on dividing or growth-arrested cells. Based on this minimal SIV vector, a sin vector was designed by deleting 151 nucleotides in the 3' LTR U3 region, and this SIV sin vector retained high transduction titers. Furthermore, the minimal SIV vector was efficient at transducing terminally differentiated human CD34(+) cell-derived or monocyte-derived dendritic cells (DCs). Results show that up to 40% of human primary DCs can be transduced by the SIV vectors. This opens a new perspective in the field of immunotherapy.
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PMID:Development of minimal lentivirus vectors derived from simian immunodeficiency virus (SIVmac251) and their use for gene transfer into human dendritic cells. 1095 29

Highly active retroviral therapy has been associated with a decline in the frequency of cytopenia in patients with human immunodeficiency virus (HIV) infection. This may result from lower hematologic toxicity of newer antiviral drugs and their increased efficacy against HIV-1. Protease inhibitors, in addition to their effects on HIV replication, appear to affect various cellular functions. Recently, it was reported that ritonavir inhibited caspase-1 expression in normal CD4(+) cells. It was hypothesized that protease inhibitors may improve hematopoietic function owing to their direct effects on the bone marrow progenitor cells. When ritonavir was added to methylcellulose cultures of bone marrow cells from HIV-infected patients and normal controls, colony formation increased 2.4-fold (n = 5) in control cultures and 4-fold (n = 5) in cultures of cells from HIV-infected patients. In the presence of ritonavir, cultures of CD34(+) cells showed markedly decreased apoptosis in comparison with untreated cultures (45% decrease in apoptotic cell number; n = 6). A synthetic inhibitor of caspase 1 (Ac-Tyr-Val-Ala-Asp-aldehyde [single-letter amino acid codes]), which inhibits activation of several caspases including CPP32 and interleukin 1beta-converting enzyme (ICE or caspase 1), also decreased the rate of apoptosis and enhanced colony formation by progenitor cells derived from HIV-infected patients (3-fold; n = 5). In ritonavir-treated samples derived from HIV-infected individuals, the number of cells expressing ICE also decreased. In conclusion, HIV protease inhibitors may, by blocking the caspase-dependent apoptotic pathway, overcome inhibition of hematopoiesis seen in patients with HIV infection, an effect unrelated to their antiviral activity. (Blood. 2000;96:2735-2739)
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PMID:Protease inhibitors stimulate hematopoiesis and decrease apoptosis and ICE expression in CD34(+) cells. 1102 6

Bone marrow or stem cell transplantation is an established therapy for haematological malignancies. We report a cytomegalovirus (CMV) IgG +ve 56-year-old patient who underwent autologous rescue with CD34(+) selected peripheral blood stem cells as part of consolidation therapy for multiple myeloma and subsequently developed CMV colitis. In contrast to infection secondary to human immunodeficiency virus (HIV), CMV colitis has not previously been described in this context. We discuss this case and issues arising from it related to the use of CD34+ selected stem cells for transplantation.
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PMID:Cytomegalovirus colitis after autologous transplantation for multiple myeloma. 1105 77

The ability of lentiviral vectors to transfer genes into human hematopoietic stem cells was studied, using a human immunodeficiency virus 1 (HIV-1)-derived vector expressing the green fluorescence protein (GFP) downstream of the phosphoglycerate kinase (PGK) promoter and pseudotyped with the G protein of vesicular stomatitis virus (VSV). High-efficiency transduction of human cord blood CD34(+) cells was achieved after overnight incubation with vector particles. Sixteen to 28 percent of individual colony-forming units granulocyte-macrophage (CFU-GM) colonies derived from cord blood CD34(+) cells were positive by polymerase chain reaction (PCR) for the GFP gene. The transduction efficiency of SCID-repopulating cells (SRC) within the cord blood CD34(+) population was assessed by serial transplantation into nonobese diabetic/severe combined immunodeficient (NOD/SCID) mice. When 400,000 cord blood CD34(+) cells were transplanted into primary recipients, all primary and secondary recipients contained and expressed the transgene. Over 50% of CFU-GM colonies derived from the bone marrow of these primary and secondary recipients contained the vector on average as determined by PCR. Transplantation of transduced cells in limiting dilution generated GFP(+) lymphoid and myeloid progeny cells that may have arisen from a single SRC. Inverse PCR analysis was used to amplify vector-chromosomal junctional fragments in colonies derived from SRC and confirmed that the vector was integrated. These results show that lentiviral vectors can efficiently transduce very primitive human hematopoietic progenitor and stem cells. (Blood. 2000;96:3725-3733)
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PMID:Lentiviral gene transfer into primary and secondary NOD/SCID repopulating cells. 1109 53

Dendritic cells (DCs) are professional antigen-presenting cells that are highly effective adjuvants for immunizing against pathogens and tumor antigens. The potential merit of genetic approaches to loading DCs with antigens is to express high and sustained levels of proteins that can be subsequently processed and presented to T lymphocytes. Replication-defective oncoretroviruses are able to efficiently transduce CD34(+) progenitor-derived DCs but not monocyte-derived DCs. Here, it is shown that efficient gene transfer is obtained using a human immunodeficiency virus-1-derived lentiviral vector deleted of all structural and accessory genes. Infection of immature DCs with the lentiviral vector at a multiplicity of infection of 20 resulted in stable gene expression in 30% to 40% of the matured DCs. Proviral DNA was detectable by Alu polymerase chain reaction for the lentiviral but not the oncoretroviral vector. Most importantly, it is demonstrated that lentivirus-transduced DCs were fully functional and effectively activated autologous HLA A2.1(+) peripheral blood cytotoxic T lymphocytes (CTLs). DCs expressing lentiviral vector-encoded Flu peptide were at least as efficient as DCs pulsed with the same peptide in stimulating specific CTLs. The efficacy of the lentivirus-transduced DCs was further demonstrated by their ability to directly activate freshly harvested peripheral blood Flu-specific CTLs in the absence of CD4(+) T-cell help and exogenous cytokines. The availability of a stable gene delivery system based on a multiply attenuated lentivirus that does not encode any viral protein and that allows sustained antigen presentation by DCs derived from blood monocytes will be very useful for the biologic investigation of DCs and the improvement of immunotherapeutic strategies involving DCs.
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PMID:Lentivirus-transduced human monocyte-derived dendritic cells efficiently stimulate antigen-specific cytotoxic T lymphocytes. 1113 50

The resistance of human bone marrow (BM) CD34(+) cells to human immunodeficiency virus (HIV) infection is at this point not fully understood. Recently we reported that the chemokines MIP-1alpha, MIP-1beta, and RANTES secreted by BM-derived CD34(+) cells may compete with the macrophagotropic HIV (R5 HIV) strain for the CCR5 coreceptor.In this study we extended our previous observations and examined various lympho-hematopoietic CD34(+) cells isolated from thymus (Th), cord blood (CB), mobilized peripheral blood (mPB), and BM for the expression of beta-chemokines binding to CCR5, i.e., MIP-1alpha, MIP-1beta, RANTES, MCP-2, MCP-3, and MCP-4, and the alpha chemokine SDF-1 (binding to CXCR4) as these chemokines may compete with the R5 and X4 HIV strains, respectively, for entry into cells. We found that Th-, CB-, mPB-, and BM-derived CD34(+) cells express mRNA transcripts for all the beta-chemokines tested but not for SDF-1. Using sensitive ELISA assays we found that although MIP-1alpha and MIP-1beta proteins were secreted by all the lympho-hematopoietic CD34(+) cells tested, RANTES was detectable only in media conditioned by BM- and CB-derived CD34(+) cells and not Th-derived cells. However, media conditioned by BM-, mPB- and Th-derived CD34(+) cells protected the T lymphocytic cell line (PB-1) from infection by the R5 but not the X4 HIV strain. Hence this study demonstrates that beta-chemokines are secreted by lympho-hematopoietic CD34(+) cells originating from various sources and that these endogenously secreted chemokines may limit entry of the R5 HIV strain into the cells by competing for the CCR5 coreceptor.
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PMID:The limited infectability by R5 HIV of CD34(+) cells from thymus, cord, and peripheral blood and bone marrow is explained by their ability to produce beta-chemokines. 1114 55

The methods available to efficiently transduce human CD34(+) hematopoietic stem cells (HSCs) derived from mobilized peripheral blood, such that they fully retain their engraftment potential and maintain high levels of transgene expression in vivo, have been unsatisfactory. The current murine retrovirus-based gene transfer systems require dividing cells for efficient transduction, and therefore the target HSCs must be activated ex vivo by cytokines to cycle, which may limit their engrafting ability. Lentivirus-based gene transfer systems do not require cell division and, thus, may allow for efficient gene transfer to human HSCs in the absence of any ex vivo cytokine stimulation. We constructed human immunodeficiency virus (HIV)-based vectors and compared them in vitro and in vivo with MuLV-based vectors in their ability to transduce unstimulated human CD34(+) HSCs isolated from mobilized peripheral blood. Both sets of vectors contained the marker gene that expresses the enhanced green fluorescent protein (EGFP) for evaluating transduction efficiency and were pseudotyped with either vesicular stomatitis virus glycoprotein (VSV-G) or the amphotropic murine leukemia virus envelope (A-MULV Env). The VSV-G-pseudotyped HIV-based vectors containing an internal mouse phosphoglycerate kinase promoter (PGK) were able to transduce up to 48% of the unstimulated CD34(+) cells as measured by EGFP expression. When these cells were injected into the human fetal thymus implants of irradiated SCID-hu Thy/Liv mice, up to 18% expressed EGFP after 8 weeks in vivo. In contrast, the MULV-based vectors were effective at transducing HSCs only in the presence of cytokines. Our results demonstrate that the improved HIV-based gene transfer system can effectively transduce unstimulated human CD34(+) HSCs, which can then differentiate into thymocytes and provide long-term transgene expression in vivo.
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PMID:Efficient human immunodeficiency virus-based vector transduction of unstimulated human mobilized peripheral blood CD34+ cells in the SCID-hu Thy/Liv model of human T cell lymphopoiesis. 1124 32

In the past decade, cellular immunophenotyping has become a new discipline in diagnostic haematology and immunology, and is invaluable in the rapid diagnosis of leukaemia and monitoring disease progression in human immunodeficiency virus infected individuals. The introduction of bench top flow cytometers has meant that immunophenotyping is now also used for the quantitation of CD34(+) peripheral blood stem cells (PBSCs) to ensure the correct timing and adequacy of haematopoietic progenitor cell harvests. Furthermore, flow cytometry has become an important tool for the counting of leucocytes in blood components after leucocyte depletion. Because this new discipline is now such a major diagnostic and prognostic tool in the clinical arena, its use must be subject to both internal and external quality control. Such a requirement was first recognised as early as 1986 when an Inter-Regional Quality Assessment Scheme (IRQAS) was initiated for laboratories that undertook the immunocytochemical diagnosis of leukaemia using the alkaline phosphates anti-alkaline phosphatase technique. This programme began with around 25 UK laboratories. In 1990, after the introduction of two more programmes (one for leukaemia diagnosis using UV microscopy and latterly flow cytometry, and one for the enumeration of CD4(+) T cells) the IRQAS achieved UK National External Quality Assessment Scheme (UK NEQAS) status and changed its title to UK NEQAS for Leucocyte Immunophenotyping. In the past decade the once small IRQAS programme has evolved into the largest international scheme of its kind, providing EQA to over 650 laboratories world wide for leukaemia immunophenotyping, lymphocyte subset analysis, PBSCs, and more recently low level leucocyte counting. Over the years, this EQA programme has highlighted important problems, such as the inappropriate use of fluorochromes and antibody titre, and the identification of effective gating strategies, all of which have contributed directly to the high interlaboratory variations seen in cellular immunophenotyping. Furthermore, particularly in absolute counting of lymphocyte subsets, PBSCs, and the enumeration of low numbers of leucocytes, UK NEQAS for Leucocyte Immunophenotyping programmes have been instrumental in highlighting the differences that occur between single and dual platform flow cytometric technologies. As a result of these findings, UK NEQAS for Leucocyte Immunophenotyping has helped to reduce the variation seen on an interlaboratory basis and enabled greater standardisation both in the UK and internationally. These advances have been attributable to the development, by UK NEQAS for Leucocyte Immunophenotyping, of a unique whole blood stabilising process that ensures the retention of the physical characteristics (both light scatter and antigenic profile) required of cells to ensure successful cellular immunophenotyping. This major technological advancement has enabled the distribution of specimens for EQA purposes on a global scale that have minimal matrix effect and behave in a manner identical to fresh blood for several months after stabilisation.
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PMID:UK NEQAS for leucocyte immunophenotyping: the first 10 years. 1142 20


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