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)

T lymphocytes in bronchoalveolar lavage (BAL) fluid from patients with sarcoidosis are activated. They are thought to recognize as yet unknown antigens and to play an important role in the pathogenesis of the disease. We studied the use of the T cell receptor V beta gene of lymphocytes obtained by BAL and lymphocytes obtained from peripheral blood of 11 patients with sarcoidosis and 9 normal controls, using the reverse transcriptase-polymerase chain reaction. As compared to the normal controls, V beta 2 and V beta 6 genes were predominantly expressed (> 15% of the sum of all V beta transcripts) on lymphocytes obtained from BAL fluid in 4 and 7 of 11 patients with sarcoidosis, respectively, but no specific V beta gene was predominantly expressed on lymphocytes obtained from peripheral blood. These results imply that those lymphocytes that are obtained from BAL fluid and that express V beta 2 and V beta 6 genes are involved in the pathogenesis of sarcoidosis.
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PMID:[Restricted T cell receptor V beta gene expression in bronchoalveolar lavage lymphocytes of patients with sarcoidosis]. 773 69

It has been previously suggested that three alternative splicings of the murine T cell receptor (TCR) zeta gene are involved in the regulation of TCR/CD3 transduction signals. We here describe a new alternative splicing of this gene (TCR iota), cloned by reverse transcriptase-polymerase chain reaction, that is encoded by exons 1-7 and 10. The protein putatively encoded by TCR iota mRNA differs in its carboxy terminus from that coded by TCR0 as a consequence of the reading frame shift of exon 10. The possible role of this new splicing in TCR modulation is briefly discussed.
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PMID:T cell receptor iota an alternatively spliced product of the T cell receptor zeta gene. 777 44

Twenty-one cytotoxic T lymphocyte (CTL) clones or lines that killed autologous tumor cells, but not allogeneic tumor, K562, or Daudi cells, were established from fresh tumor-infiltrating lymphocytes of two individuals (HP-1 and HP-2) with head and neck cancer by limiting dilution in the presence of recombinant interleukin-2. Sixteen (76%) of these 21 clones or lines comprised CD4+ CTLs and the other five comprised CD8+ CTLs. These observations suggest that autologous tumor cell-specific CD4+ CD8- and CD4- CD8+ CTLs are present in vivo at the tumor site in head and neck cancer. Analysis of T cell receptor (TCR) gene arrangements in 20 of the 21 CTL isolates with reverse transcriptase and the polymerase chain reaction revealed that five of 12 and five of eight isolates from HP-1 and HP-2, respectively, were clones, the other isolates being lines comprised of two or more clones. Each CTL clone showed a different combination of V alpha and V beta gene expression, suggesting that more than five different tumor-associated antigens may be expressed on head and neck cancer cells. In spite of the diversity of TCR alpha beta combinations, TCR V alpha 1, V alpha 3, V alpha 8, V alpha 10, V beta 8, V beta 9, and V beta 17 were also frequently expressed in both patients. These data suggest that specific CTLs proliferate oligoclonally and contribute to the specific immune response against head and neck cancer in vivo.
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PMID:Functional and T cell receptor gene usage analysis of cytotoxic T lymphocytes in fresh tumor-infiltrating lymphocytes from human head and neck cancer. 779 Mar 20

To clarify whether there is a bias in the V-D-J combination of T cell receptor (TcR) genes, J beta gene usage has been investigated in a total of 743 TcR beta genes of V beta 2, V beta 8.2, and V beta 14 families expressed in C57BL/6 mouse spleens. Genes of TcR beta chains, amplified by a reverse transcriptase-polymerase chain reaction, were individually cloned into plasmids. Cloned genes (61 to 106), randomly selected in each respective V beta family from three different mice, were tested by means of hybridization with 12 oligo DNA probes which were designed to differentiate 12 murine functional J beta gene segments. The results are enumerated below. (1) The J beta 2.6 gene segment was found to be most frequently used (V beta 2, 19.8%; V beta 8.2, 21.2%; and V beta 14, 19.2%). In contrast, usage of the J beta 1.6 gene segment was most infrequent (V beta 2, 1.9%; V beta 8.2, 2.9%; and V beta 14, 0.5%); (2) High frequency of the J beta 2.1 gene segment and low frequency of the J beta 1.3 and J beta 1.5 gene segments were also observed; (3) The J beta 2 cluster was used in preference to the J beta 1 cluster (usages of the J beta 2 cluster: V beta 2, 67.8%; V beta 8.2, 65.9%; and V beta 14, 70.4%); and (4) These biases were generally common to all three V beta families examined and differences among individual mice were mostly small. Considering these findings, we conclude that the TcR J beta gene segments in C57BL/6 mice splenocytes are selected with a bias, but are selected independently of the V beta families.
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PMID:Comparison of the J beta gene usage among different T cell receptor V beta families in spleens of C57BL/6 mice. 792 68

The immune response to an allograft is regulated by cytokines produced by cells infiltrating the allograft. However, the immunopathogenesis of allograft rejection is not completely understood. To investigate the role of cytokines after clinical heart transplantation, we analysed the expression of cytokine genes in sequentially taken endomyocardial biopsies (EMB) by using the reverse transcriptase-polymerase chain reaction (RT-PCR). We analysed 44 EMB from 11 recipients: 21 EMB before or during rejection, and 23 EMB without histological evidence of acute rejection. A strong correlation was found between IL-2 gene expression and histologically proved rejection (16/21 versus 1/23 without rejection, P < 0.001; chi 2 test). Also, expression of IL-4 and IL-6 genes was more often found in EMB during rejection than in EMB without signs of rejection (IL-4, 62% versus 35%; and IL-6, 81% versus 39%, respectively). No relation with rejection or with immunological quiescence was observed for the presence of IL-10 gene transcripts. IL-10, but also IL-6 mRNA were detectable in donor heart tissue before transplantation (9/10). In contrast, IL-2 and IL-4 gene transcripts were absent in these samples. These differences could not be explained by the presence or absence of T cells, since the gene for the constant region of the beta-chain (C beta) of the T cell receptor (TCR) not only was expressed in post-transplant EMB but also in pre-transplant donor heart tissue. Our results provide strong evidence that the immunoregulatory cytokines IL-2, IL-4 and IL-6 are important local regulators in the graft during acute rejection. The role of IL-10 in the immunologic response to the transplanted organ needs further investigation.
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PMID:Cytokine mRNA expression in endomyocardial biopsies during acute rejection from human heart transplants. 805 Jan 79

Taking advantage of the reverse transcriptase-polymerase chain reaction (RT-PCR), we have analyzed T cell receptor gamma-chain mRNA of synovial fluid gamma/delta T cells from patients with rheumatoid arthritis (RA) in comparison with those of peripheral blood mononuclear cells (PBMC) from RA patients and healthy individuals. The quantitative RT-PCR method in conjunction with nucleotide sequencing revealed the frequent usage of the V gamma 3 gene segment in RA synovial fluid mononuclear cells (SFMC) (p < 0.01) which in PBMC of healthy individuals occurred rarely. PBMC of most healthy individuals expressed the V gamma 9 gene predominantly (p < 0.01) as expected. However, only half of RA patients showed elevated levels of the V gamma 9 gene expression in their PBMC. The gamma-chain mRNA containing the V gamma 3 gene in RA SFMC showed no conserved junctional sequence (complementarity-determining region 3). To investigate the nature of ligands recognized by the V gamma 3-bearing T cells, we analyzed V gamma gene usage of RA SFMC, RA PBMC, and normal PBMC stimulated with Mycobacterium tuberculosis (MT) or MT plus interleukin-2 since there is mounting evidence of high reactivity of RA SFMC to MT and mycobacterial heat-shock protein 65. However, the V gamma usage appeared to be mostly V gamma 9 in RA SFMC, RA PBMC and normal PBMC. Taken together these results suggest that an as yet unknown antigen(s) (other than MT) might select gamma/delta T cells expressing the V gamma 3 gene in RA SFMC.
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PMID:The biased V gamma gene usage in the synovial fluid of patients with rheumatoid arthritis. 818 23

To determine whether T cells, like B cells, can become clonally expanded in normal individuals as a function of age, we compared the T cell V beta repertoire of cord blood to that of peripheral blood from normal donors over 65 yr of age. T cells from elderly subjects contained expanded subsets (greater than the mean+three standard deviations) of T cell receptor (TCR) V beta populations. These expanded subsets were observed primarily among CD8, but not CD4 cells, represented up to 37.5% of all CD8 cells, and were present in most elderly subjects. An expanded V beta 5.2/3 CD8 subset and a V beta 6.7a CD8 subset from separate donors were analyzed by reverse transcriptase-polymerase chain reaction, cloning and sequencing of the TCR beta chain VDJ junction. In both cases the expanded subsets were mono- or oligoclonal while control CD4 populations were polyclonal. Using two-color flow cytometry it was possible to identify the expanded V beta 6.7a subset as CD8+ CD28-CD11b+ cells. In three of five random old subjects similar expansions of V beta subsets were found specifically in the CD8+ CD28- subpopulation, an interesting subset of cytotoxic T lymphocytes, known to lack proliferative responses to TCR stimuli. It is common practice to use the demonstration of clonality as a diagnostic indicator for T cell lymphoma/leukemia. In view of the high frequency of expanded T clones of T cells in normal elderly subjects the diagnostic usefulness of this test should be reexamined.
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PMID:Clonal populations of T cells in normal elderly humans: the T cell equivalent to "benign monoclonal gammapathy". 829 71

Cytokines may play critical roles in allograft rejection. Currently, a clear pattern of cytokine production that correlates with rejection has not emerged. Our preliminary studies suggested a trend toward increased IL-6 and TGF-beta gene expression in cardiac allografts during rejection. We have extended these studies using reverse transcriptase/polymerase chain reaction (RT/PCR) to detect the expression of IL-6, TGF-beta, and T cell receptor beta chain constant region (TCR-beta) genes in 21 additional consecutive myocardial biopsies obtained from six heart transplant patients and from five pre-transplant donor hearts. Cytokine gene expression was compared with histological diagnosis of rejection. There was strong correlation between IL-6 as well as TGF-beta gene expression, and histological rejection (6/8 biopsies with versus 0/7 without rejection (P = 0.006) and 7/9 biopsies with versus 0/7 without rejection (P = 0.003) respectively). Neither IL-6 nor TGF-beta transcripts were detected in any pre-transplant donor heart. TCR-beta chain mRNA was found in all allograft biopsies regardless of the presence of rejection, but was absent in pre-transplant donor hearts. Our results indicate that expression of IL-6 and TGF-beta is highly correlated with allograft rejection and thus may play an important role in regulation of cardiac allograft rejection. T cell infiltration of allografted myocardium is invariably detected by PCR regardless of histological rejection. The long-term functional significance of these cells in transplanted hearts needs further investigation.
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PMID:Expression of cytokine genes in human cardiac allografts: correlation of IL-6 and transforming growth factor-beta (TGF-beta) with histological rejection. 837 Jan 74

Allograft rejection is dependent on T cell activation, which requires both the engagement of the T cell receptor by antigen in the context of the MHC molecules and costimulatory signals delivered by cell surface molecules such as B7-CD28/CTLA4 pathway. CTLA4-Ig is a fusion protein that blocks this pathway and has previously been shown to prolong both allograft and xenograft survival. The current study demonstrates markedly prolonged murine cardiac allograft survival and specific prolongation of secondary skin grafts using a combination of CTLA4-Ig plus donor bone marrow. A role for hematopoietic chimerism in the establishment of CTLA4-Ig-induced transplantation tolerance was investigated using reverse transcriptase polymerase chain reaction analysis of recipient tissues. Expression of donor-specific MHC class II transcripts in both peripheral and lymphoid tissues was demonstrated at greater than 200 days after transplant. To investigate the functional significance of this observation, heart donors, and donor bone marrow were irradiated before transplantation in CTLA4-Ig-treated recipients. A reduction in allograft survival was associated with irradiation of both the donor heart and the bone marrow. These results suggest that there may be a donor-derived radiosensitive element that enhances allograft survival in this model. Reverse transcriptase polymerase chain reaction analysis of allografts of tolerant and control animals at days 5, 8, and 12 after transplantation failed to demonstrate a dramatic difference in the expression of interleukin (IL)-2, IL-4, IL-10, and interferon-gamma message. Cytotoxicity effector transcripts were largely intact in CTLA4-Ig + bone marrow-treated recipients as they showed no decrease in intragraft granzyme, perforin, Fas, or Fas ligand transcripts during thr first 8 days after transplant. These results imply that complex mechanisms may be important for the induction and maintenance of transplantation tolerance in the CTLA4-Ig plus bone marrow murine cardiac allograft model.
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PMID:CTLA4-Ig plus bone marrow induces long-term allograft survival and donor specific unresponsiveness in the murine model. Evidence for hematopoietic chimerism. 862 6

During normal pregnancy, the fetus continues to mature inside the uterus without rejection. Inherited paternal antigens could be targeted by the maternal immune system. These reactions are believed to play a role in a number of habitual abortions. However, the precise maternal mechanisms preventing fetal tissue rejection are not well understood. Maternal T cells should recognize fetal antigens, so it is conceivable that antigen-specific T cell response to fetal antigens would occur by proliferation and accumulation of certain T cell clones in the pregnant mother. To elucidate the maternal immune response to the fetus we investigated the clonality of expanded T cells in peripheral blood lymphocytes in ten normal pregnant women. We employed reverse transcriptase-polymerase chain reaction for T cell receptor beta chain gene and subsequently analyzed the PCR product by single-strand conformation polymorphism analysis. A large number of distinctly expanded T cell clones were detected during pregnancy. These accumulations were observed as early as the ninth to tenth week post-conception and reached a maximum during the second trimester, suggesting the existence of dynamic antigen-specific T cell responses in the pregnant mother. However, after the 30th week of gestation, nearly all expanded T cell clones disappeared before parturition and the degree of clonality reached almost normal levels. Our results clearly indicate the existence of dynamic maternal T cell responses during pregnancy.
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PMID:Time course analysis of alpha+ beta+ T cell clones during normal pregnancy. 862 75


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