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)

Although tumor necrosis factor-alpha (TNF) is constitutively expressed in human and mouse thymus, the effects of TNF on thymocyte proliferation, differentiation and survival suggest that its influence in the thymus is complex. To determine if this complexity results from changes in the expression of the two TNF receptors during thymocyte differentiation, we examined the expression of the 55 kDa TNF receptor (TNF-R1) and the 75 kDa TNF receptor (TNF-R2) on postnatal human thymocytes. Both TNF-R1 and TNF-R2 mRNA were found in resting human thymocytes by reverse transcriptase-polymerase chain reaction (RT-PCR). Using mAb which specifically react with the respective TNF receptors and a highly sensitive, three-step method of immunofluorescence, cell surface TNF-R1 was detected on the vast majority of thymocytes. In contrast, detectable cell surface TNF-R2 was present on a mean of only 12.9% of thymocytes. TNF conjugated to phycoerythrin (TNF-PE) also reacted with a small population of thymocytes and was found to specifically block binding of the TNF-R2 mAb and not the TNF-R1 mAb, implicating preferential binding of TNF-PE to TNF-R2. Using dual-color immunofluorescence with TNF-PE we found that the population of cells which express TNF-R2 also express high levels of the TCR alpha, beta-CD3 complex, CD4 or CD8, and IL-2 receptor alpha chain. Thus, immature (TCRneg/low) thymocytes express TNF-R1 while mature (TCRhigh) thymocytes can also express TNF-R2. This differential expression of TNF receptors provides a mechanism for distinct effects of TNF on immature vs. mature thymocytes.
Thymus
PMID:Characterization of TNF receptors on human thymocytes. 852 4

T-cell mediated cytotoxicity play an important role in the control of human immunodeficiency virus (HIV) infection. The polyclonal cytotoxic T lymphocyte (CTL) response against target cells infected with a recombinant vaccinia virus expressing Env, Gag, Nef or reverse transcriptase (RT) proteins has been studied in four groups of individuals: acquired immune deficiency syndrome (AIDS) patients, AIDS-related complex (ARC) patients, HIV-1 seropositive subjects and seronegative controls. CTL lines have been generated by non-specific stimulation with phytohemagglutinin and interleukin-2 and target cells have been prepared from autologous B lymphocytes. CTL from asymptomatic and ARC individuals recognized most of the various proteins of HIV-1 but those from AIDS patients had very low or absent responses to the majority of proteins, with the anti-Nef cytotoxic activity decreasing first. Two of 10 AIDS patients had demonstrable recognition of Gag p24, one of RT and eight patients had no recognition of any of the proteins. The effector cells were demonstrated to be predominantly of the CD8+ phenotype, using the appropriate monoclonal antibodies. When heterologous target cells were substituted for autologous cells, the cytotoxic response was abrogated in the vast majority of cases demonstrating its human leucocyte antigen (HLA) class I restriction. Among the 10 HIV-seronegative subjects, nine had no CTL activity against the various HIV-1 proteins but one subject was able to recognize Env and RT. In the evolution of HIV infection from the seropositive stage to AIDS, CTL polyclonal activities progressively decrease, with Nef responses disappearing first, then Env and Gag p55, followed by RT and Gag p24.
Thymus 1997
PMID:Loss of T-cell cytotoxic responses in the course of HIV-1 infection. 949 84

Thymus regression upon stressing stimuli, such as infectious diseases, is followed by organ reconstitution, paralleling its development in ontogeny. A narrow window of thymus development was here studied, encompassing the pro-T lymphoid precursor expansion during specification stages, by the use of epidermal growth factor plus insulin (INS) in murine fetal thymus organ cultures. Aiming to disclose signaling pathways related to these stages, cultured thymus lobes had their RNA extracted, for the search of transcripts differentially expressed using RNAse protection assays and reverse transcriptase-polymerase chain reactions. We found no difference that could explain INS-driven thymocyte growth, in the pattern of transcripts for death/proliferation mediators, or for a series of growth factor receptors and transcriptional regulators known as essential for thymus development. Thymocyte suspensions from cultured lobes, stained for phenotype analysis by fluorescence activated cell sorting, showed a decreased staining for Notch1 protein at cell surfaces upon INS addition. We analyzed the expression of Notch-related elements, and observed the recruitment of a specific set of transcripts simultaneous and compatible with INS-driven thymocyte growth, namely, transcripts for Notch3, for its ligand Jagged2, and for Deltex1, a mediator of a poorly characterized alternative pathway downstream of the Notch receptor.
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PMID:Differential expression of notch signaling-related transcripts accompanies pro-thymocyte proliferation and phenotype transition induced by epidermal growth factor plus insulin in fetal thymus organ cultures. 1532 27

OY-TES-1 is a novel target that belongs to the family of 'cancer/testis' (CT) antigens. Our goal was to examine the expression and immunogenicity of OY-TES-1 in epithelial ovarian cancer (EOC) to determine its potential as a target for vaccine therapy. OY-TES-1 expression was determined by one-step reverse transcriptase PCR on 100 EOC samples, 5 EOC cell lines, and a panel of normal tissues. Immunohistochemistry (IHC) was performed on the same panel of EOC tissues. Sera from a sub-group of patients were tested for OY-TES-1 antibody by ELISA. Thymus and leukocytes were weakly positive for OY-TES-1 while the remaining 5 normal tissues were negative. Expression of OY-TES-1 by either RT-PCR and/or IHC was demonstrable in 69/100 (69%) tumors. Humoral immunity to OY-TES-1 was demonstrated in 1/10 (10%) serum samples from patients whose tumors expressed the antigen. The median follow-up of the patient population was 34 months. There was no correlation between antigen expression and stage, grade, histology and survival. OY-TES-1 is expressed in 69% of patients with EOC, is absent from normal ovarian tissue, and a proportion of patients show evidence of a specific humoral immune response. These findings make OY-TES-1 an attractive target for antigen-specific immunotherapy in EOC.
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PMID:OY-TES-1 expression and serum immunoreactivity in epithelial ovarian cancer. 1696 86

Two experiments were conducted to determine the persistence and tissue distribution of serotypes 1 and 2 of infectious bursal disease virus (IBDV) in specific-pathogen-free and vaccinated turkeys. In Experiment 1, three groups of 2-wk-old turkey poults, including a negative control group, were used. In groups 1 and 2, 13 poults in each group were challenged with either serotype 1 (STC) or serotype 2 (OH) strains using an inoculum of 10(4) 50% embryo infectious dose (EID50)/0.2 ml/bird. Thymus, bursa, spleen, kidney, lungs, liver, pancreas, caecum, and breast and thigh muscles were sampled at predetermined intervals. The bursal tissues from birds inoculated with either serotype were reverse transcriptase-PCR (RT-PCR) positive up to 21 days postinoculation (DPI). In both groups virus isolation from bursas was possible up to 14 DPI. Except for the bursas and spleens in birds inoculated with serotype 1 and bursas in birds inoculated with serotype 2, all other tissues were RT-PCR negative. In Experiment 2, five groups of turkey poults were used. At 4 wk of age, group 1 was challenged with a serotype 1 STC strain and group 2 with serotype 2 OH strain using an inoculum size of 10(2) EID50/0.2 ml for both serotypes. Groups 3 and 4 were vaccinated at 2 wk of age using an inactivated serotype 1 IBDV vaccine. At 2 wk postvaccination, groups 3 and 4 were challenged with STC and OH strains respectively. From group 1, bursal, spleen, and liver tissues were RT-PCR positive up to 14 DPI; breast muscle and kidney tissues were positive up to 7 DPI; and lungs and pancreatic tissues were positive up to 3 DPI. From group 2, bursal tissues were RT-PCR positive up to 14 DPI and lung tissues up to 3 DPI. All of the tissue samples collected from groups 3, 4, and 5 were RT-PCR negative. Virus could not be isolated from RT-PCR positive bursal homogenate. In this work, it was confirmed that the virus persisted in the bursa longer than in any other tissues. The difference in the results between Experiments 1 and 2 could be due to the age of poults at vaccination and the higher inoculum size used in Experiment 1. This study indicates that turkeys are more resistant to IBDV as compared to chickens. Viruses of serotypes 1 and 2 infect turkeys and persist in bursal tissue for 14 days and RNA was detected up to 21 days.
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PMID:Persistence and Tissue Distribution of Infectious Bursal Disease Virus Serotypes 1 and 2 in Turkeys. 2629 50