Search results for " T-Cell"
showing 10 items of 320 documents
IL-23 receptor regulates unconventional IL-17-producing T cells that control bacterial infections.
2010
AbstractIL-23 plays an important role in autoimmune tissue inflammation and induces the generation of not fully characterized effector cells that mediate protection against pathogens. In this paper, we established the essential role of IL-23R in the host response against intracellular pathogens. IL-23 was critical for the expansion or maintenance of γδ and double negative (DN) αβ T cells. These cells were rapidly recruited to the site of infection and produced large amounts of IL-17, IFN-γ, and TNF-α. Notably, DN T cells transferred into L. monocytogenes-infected RAG2−/− mice prevented bacterial growth, confirming their protective role against intracellular pathogens. Our results show that …
Peripheral T-cell lymphoma classification: the matter of cellular derivation.
2011
Peripheral T-cell lymphomas (PTCLs) represent approximately 12% of all non-Hodgkin's lymphomas in Western countries. They are quite heterogeneous as far as morphology and phenotype are concerned. Furthermore, until now, PTCLs could not be referred to specific normal counterparts, in contrast to B-cell-derived non-Hodgkin's lymphomas. In particular, in the last edition of the WHO classification of Tumors of the Hematopoietic and Lymphoid Tissues, for the majority of nodal PTCLs (including the not otherwise specified type and anaplastic large-cell lymphoma), the postulated cell of origin remained undefined. However, in the last few years, high-throughput genomic techniques, especially gene-ex…
T cell avidity determines the level of CTL activation
2004
To investigate the influence of avidity on T cell activation in vitro and in vivo, we analyzed T cells from St40 and St42 mice, which express the same transgenic TCR specific for an E1a-derived epitope of adenovirus type 5 with different expression levels and therefore different avidities. Splenocytes from both strains showed comparable cytolytic activities and required identical peptide concentrations for efficient target cell lysis and up-regulation of activation markers. However, the kinetics of CD25 up-regulation were strikingly different: whereas the majority of the high-avidity St42 T cells up-regulated the IL-2Ralpha chain within a few hours, low-avidity St40 T cells expressed only 5…
Human intestinal Vdelta1+ lymphocytes recognize tumor cells of epithelial origin.
1996
gammadelta T cells can be grouped into discrete subsets based upon their expression of T cell receptor (TCR) variable (V) region families, their tissue distribution, and their specificity. Vdelta2+ T cells constitute the majority of gammadelta T cells in peripheral blood whereas Vdelta1+T cells reside preferentially in skin epithelium and in the intestine. gammadelta T cells are envisioned as first line host defense mechanisms capable of providing a source of immune effector T cells and immunomodulating cytokines such as interleukin (IL) 4 or interferon (IFN) gamma. We describe here the fine specificity of three distinct gammadelta+ tumor-infiltrating lymphocytes (TIL) obtained from patient…
TCR V alpha chain expression influences reactivity to the hapten TNP.
1997
We have recently demonstrated a remarkable selection of in vitro cultivated, TNP-specific polyclonal T cell lines for the expression of a TCR beta chain encoded by the V beta 8.2 gene. The goal of the present study was to analyse V alpha usage in V beta 8.2 T cells responsive to TNP, using TNP-specific T cell lines derived from three common strains of mice, as well as from V beta 8.2 transgenic mice. Results indicate that in vitro TNP stimulation of T cells from TNP-immune mice results in significant skewing of V alpha usage among responding V beta 8.2+ T cells, with overexpression observed for V alpha 3.2 and V alpha 8. These results indicate that V alpha expression influences recognition …
Liver-primed memory T cells generated under noninflammatory conditions provide anti-infectious immunity.
2013
SummaryDevelopment of CD8+ T cell (CTL) immunity or tolerance is linked to the conditions during T cell priming. Dendritic cells (DCs) matured during inflammation generate effector/memory T cells, whereas immature DCs cause T cell deletion/anergy. We identify a third outcome of T cell priming in absence of inflammation enabled by cross-presenting liver sinusoidal endothelial cells. Such priming generated memory T cells that were spared from deletion by immature DCs. Similar to central memory T cells, liver-primed T cells differentiated into effector CTLs upon antigen re-encounter on matured DCs even after prolonged absence of antigen. Their reactivation required combinatorial signaling thro…
Tumors as elusive targets of T-cell-based active immunotherapy.
2003
The understanding of tumor-host interactions remains elusive despite significant progress in the identification of tumor antigens (TAs) recognized by autologous T cells. In particular, most human tumors do not regress and continue to grow in spite of spontaneous or immunization-induced immune responses demonstrated in circulating lymphocytes. Indeed, systemic immune responses might insufficiently address the complexity of tumor-host interactions because of factors, such as (1) the lack of productive T-cell receptor (TCR) engagement with epitope owing to qualitative and/or quantitative defects in the generation and maintenance of the immune response, (2) insufficient costimulation provided b…
Phenotypical and Functional Alteration of γδ T Lymphocytes in COVID-19 Patients: Reversal by Statins
2022
(1) Background: statins have been considered an attractive class of drugs in the pharmacological setting of COVID-19 due to their pleiotropic properties and their use correlates with decreased mortality in hospitalized COVID-19 patients. Furthermore, it is well known that statins, which block the mevalonate pathway, affect γδ T lymphocyte activation. As γδ T cells participate in the inflammatory process of COVID-19, we have investigated the therapeutical potential of statins as a tool to inhibit γδ T cell pro-inflammatory activities; (2) Methods: we harvested peripheral blood mononuclear cells (PBMCs) from COVID-19 patients with mild clinical manifestatio…
Regulation of calcium signalling by docosahexaenoic acid in human T-cells: implication of CRAC channels
2000
Abstract We elucidated the role of docosahexaenoic acid (DHA) on the increases in free intracellular calcium concentrations, [Ca2+]i, in human (Jurkat) T-cell lines. DHA evoked an increase in [Ca2+]i in a dose-dependent manner in these cells. Anti-CD3 antibody, known to stimulate increases in Ca2+ from endoplasmic reticulum (ER) via the production of inositol trisphosphate, also evoked increases in [Ca2+]i in Jurkat T-cells. We also used thapsigargin which inhibits Ca2+-ATPase of the ER and, therefore, increases Ca2+ in the cytosol. Interestingly, addition of DHA during the thapsigargin-induced peak response exerted an additive effect on the increases in [Ca2+]i in human T-cells, indicating…
Perpetual proliferation of LYT-1 cells requires repetitive signals for IL-2 receptor induction by antigen-presenting cells.
1984
Abstract T cell lines with specificity for bovine insulin and ovalbumin were maintained by serial stimulation with antigen presented on irradiated syngeneic spleen cells, alternating 3 days later with subculture in IL-2 containing medium (CM). When the cultures were repetitively split in CM, with concomitant dilution of antigen-presenting cells, a gradual loss of proliferative capacity of the cells in the presence of CM was observed. Absorption studies revealed a 20-fold reduction of IL-2 receptors on the surface of T blasts assayed 12 days after antigenic stimulation as compared with day 5 blasts. This decrement in the number of IL-2 acceptor sites reflected an actual decrease in cell surf…