Search results for "Activation"
showing 10 items of 2079 documents
The role of ICOS in directing T cell responses: ICOS-dependent induction of T cell anergy by tolerogenic dendritic cells.
2009
Abstract Tolerogenic dendritic cells (DC) play an important role in maintaining peripheral T cell tolerance in steady-state conditions through induction of anergic, IL-10-producing T cells with suppressive properties. ICOS, an activation-induced member of the CD28 family on T cells, is involved in the induction of IL-10, which itself could contribute to induction of anergy and development of suppressive T cells. Therefore, we analyzed the functional role of ICOS in the differentiation process of human CD4+ T cells upon their interaction with tolerogenic DC. We compared the functional properties of CD4+ T cells from healthy volunteers and ICOS-deficient patients after stimulation with tolero…
T cell activation defect in hemodialysis patients: Evidence for a role of the B7/CD28 pathway
1993
T cell activation defect in hemodialysis patients: Evidence for a role of the B7/CD28 pathway. The immunosuppressive effect of chronic renal failure is correlated with an impaired proliferation of peripheral blood leukocytes in vitro . This is mainly due to an impaired function of the accessory cells rather than the T cells. Here we tried to define a missing accessory signal for T cell activation in hemodialysis patients. We substituted cell surface bound molecules by adding tumor cell lines to the in vitro assays that express different patterns of accessory molecules. Cell lines that express the costimulatory B7 molecule reconstituted the activation of patients' cells whereas B7 negative c…
CD2-mediated autocrine growth of herpes virus saimiri-transformed human T lymphocytes.
1992
Herpes virus saimiri (HVS) immortalizes T lymphocytes from a variety of primates and causes acute T cell lymphomas and leukemias in nonnatural primate hosts. Here we have analyzed the requirements for growth of three HVS-transformed human T cell lines. The cells expressed the phenotype of activated T cells: two were CD4+, and one was CD8+. All three cells responded to all allogeneic human cell lines tested with enhanced proliferation, production of interleukin 2 (IL-2), and increased expression of the IL-2 receptor. Binding of CD2 to its ligand CD58 was the critical event mediating stimulation because: (a) monoclonal antibodies (mAbs) to CD2 and to CD58, but not to a variety of other surfac…
Herpes virus saimiri-transformed human T lymphocytes: normal functional phenotype and preserved T cell receptor signalling
1993
Herpes virus saimiri (HVS), a primate herpes virus, transforms human CD4+ and CD8+ T lymphocytes to continuous growth in vitro. We have previously shown that HVS-transformed human T cells (HVS-T cells) respond to stimulation via CD2 with autocrine growth. In the present study we have investigated the functional characteristics of HVS-T cells. We describe that these cells can perform all the functions of normal T cells, i.e. cytokine secretion, cytotoxicity, and exocytosis of granule esterases. All these activities can be triggered via CD2 by binding to its natural ligand or via the TCR, e.g. by anti-TCR antibodies, by recognition of a bacterial superantigen and by MHC-restricted recognition…
Defective T cell receptor/CD3 complex signaling in human type I diabetes
1994
The autoimmune process leading to the destruction of pancreatic β-cells is mediated by T lymphocytes. Peripheral T cells from subjects with preclinical and clinical type I diabetes respond weakly in vitro to lectin stimulation. We, therefore, investigated in a group of newly diagnosed diabetic patients the presence of a defect in the signal transduction pathway of the T cell receptor (TcR)/CD3 complex. Following stimulation with anti-CD3-coupled beads, the proliferative response in diabetic T cells was significantly decreased in comparison with that from normal T cells. Interestingly, addition of either recombinant interleukin (IL)-2 or phorbol 12-myristate 13-acetate to the cell culture wa…
Importance of the inducible costimulator molecule for the induction of allergic immune responses and its decreased expression on T helper cells after…
2004
The inducible costimulator (ICOS), a newly identified member of the CD28 receptor family that is induced after T-cell activation, and its ligand (ICOSL), being expressed on activated monocytes and dendritic cells play a key role in T-cell-mediated immune responses. As ICOS costimulation also seems to regulate T helper 2 effector cells, the aim of this study was to analyse the function of this molecule in allergic immune responses and their specific therapy, mainly venom immunotherapy (VIT). CD4+ T cells from grass pollen-, or bee or wasp venom-allergic donors were stimulated in the presence of autologous mature dendritic cells, which were pulsed with different allergen doses. In this system…
Resistance to Gemcitabine in a Lymphoma Cell Line Resistant to Fas-mediated Apoptosis
2004
BACKGROUND: The T-cell lymphoma cell line HuT78B1, selected for resistance to Fas-mediated apoptosis, resulted unexpectedly resistant to the apoptotic and cytotoxic effects of gemcitabine (dFdC). We investigated whether this resistance was due to the impairment of the Fas/Fas-ligand (FasL) system. MATERIALS AND METHODS: dFdC effects were studied in HuT78B1 and in the parental Fas-sensitive HuT78 cells exposed to inhibitors of the Fas/FasL system. RESULTS: FasL- and Fas-blocking antibodies did not interfere with dFdC-induced apoptosis in HuT78 cells, whereas inhibitors of caspase-8, -9, -1 or -3 had partial inhibitory effects. Notably, in HuT78B1 cells there was a markedly reduced dFdC accum…
Correlation spectroscopy in molten and supercooled antimony trichloride.
1990
Correlation spectroscopy measurements performed on molten and supercooled antimony trichloride with the homodyne technique show correlation functions that have a nonexponential behavior. Two well-defined distributions of correlation times can be observed in different temporal regions. This behavior is discussed in terms of a structural relaxation of clusters dynamically formed by intermolecular and interchain bonds. The Arrhenius plot of these correlation times shows a linear behavior with the same activation energy for both. In contrast, the activation energy of shear viscosity has a different value, showing that the processes determining the temperature behavior of \ensuremath{\tau} and $…
PTEN Mediates the Antioxidant Effect of Resveratrol at Nutritionally Relevant Concentrations
2014
Introduction.Antioxidant properties of resveratrol have been intensively studied for the last years, bothin vivoandin vitro. Its bioavailability after an oral dose is very low and therefore it is very important to make sure that plasma concentrations of free resveratrol are sufficient enough to be active as antioxidant.Aims.In the present study, using nutritionally relevant concentrations of resveratrol, we aim to confirm its antioxidant capacity on reducing peroxide levels and look for the molecular pathway involved in this antioxidant effect.Methods.We used mammary gland tumor cells (MCF-7), which were pretreated with different concentrations of resveratrol for 48 h, and/or a PTEN inhibit…
DNA replication arrest in response to genotoxic stress provokes early activation of stress-activated protein kinases (SAPK/JNK).
2009
Abstract The impact of DNA damage-induced replication blockage for early activation of stress kinases [stress-activated protein kinase (SAPK)/c-Jun N-terminal kinase (JNK)] is largely unknown. Here, we show that induction of dual phosphorylation of SAPK/JNK by the DNA polymerase inhibitor aphidicolin was not ameliorated by additional exposure to ultraviolet (UV) light, indicating that overlapping mechanisms participate in signaling to SAPK/JNK triggered by both agents. UV-induced DNA replication blockage, cyclobutane pyrimidine dimer formation and DNA strand break induction coincided with SAPK/JNK phosphorylation at early (≤ 30 min) but not late (≥ 2 h) time points after exposure. Genotoxin…