Search results for "t-lymphocytes"
showing 10 items of 1380 documents
Effects of polyphenols and lipids from Pennisetum glaucum grains on T-cell activation: modulation of Ca2+ and ERK1/ERK2 signaling
2015
International audience; BACKGROUND: Pearl millet (PM), i.e., Pennisetum glaucum, is widely grown in Africa and known for its anti-oxidant and anti-hyperlipidemic properties.METHODS: The P. glaucum grains were obtained from the region of Ouled Aïssa (South of Algeria). We assessed the effects of phenolic compounds and lipids, extracted from seeds of P. glaucum, on rat lymphocyte proliferation, activated by phorbol 12-myristate 13-acetate and ionomycin. In order to explore signaling pathway, triggered by these compounds, we assessed interleukin-2 (IL-2) mRNA expression and extracellular signal-regulated kinase-1/2 (ERK1/ERK2) phosphorylation. Finally, we determined increases in free intracell…
CD8+CD45RA+CD27-CD28-T-cell subset in PBL of cervical cancer patients representing CD8+T-cells being able to recognize cervical cancer associated ant…
2003
Objective In response to antigenic stimulation, naive MHC-class I restricted and antigen-specific CD8+CD45RA+CD28+T-cells undergo clonal expansion and differentiate into CD8+CD45RO+ memory T-cells. Upon re- encounter with the nominal antigen, CD45RO+ T-cells are able to convert to CD8+CD45RA+CD28-T-cells displaying potent immune effector functions, including TNF-alpha production. This T-cell subpopulation constitutes a minor population in healthy individuals. In the present study we are currently evaluating whether this particular T-cell subset in PBL represents CD8+T-cells which may be able to recognize cervical cancer associated antigens provided by HPV 16 E7. Material and methods Flow-cy…
Novel path to apoptosis: small transmembrane pores created by staphylococcal alpha-toxin in T lymphocytes evoke internucleosomal DNA degradation.
1994
Peripheral-blood human T lymphocytes were treated with Staphylococcus aureus alpha-toxin. Membrane permeabilization was assessed by measuring efflux of K+ and Rb+ and influx of Na+, Ca2+, and propidium iodide. Cellular ATP and [3H]thymidine incorporation following lectin stimulation were measured as parameters for cell viability. Internucleosomal cleavage characteristic of programmed cell death was assessed by agarose gel electrophoresis and by quantifying low-molecular-weight, [3H]thymidine-labeled DNA fragments. Nanomolar concentrations of alpha-toxin evoked protracted, irreversible ATP depletion in both activated and resting T lymphocytes. Toxin-damaged cells also lost their ability to i…
Cytocidal effects of Escherichia coli hemolysin on human T lymphocytes.
1993
Escherichia coli hemolysin is the prototype of a large family of pore-forming toxins produced by gram-negative organisms. Besides its known cytotoxic activities against granulocytes, monocytes, endothelial cells, and renal epithelial cells, we now demonstrate that the toxin potently kills human T lymphocytes. Evidence based on different and independent approaches indicates that lymphocidal activity is due to formation of transmembrane pores. Additionally, cells prestimulated with phytohemagglutinin respond to low doses of E. coli hemolysin with DNA fragmentation similar to that observed in cells undergoing programmed cell death. Kinetic considerations lead us to conclude that DNA degradatio…
Natural and induced apoptosis during lymphocyte development in the axolotl
1999
Lymphocytes apoptosis was characterized in a urodele amphibian, the axolotl, by morphology using electron microscopy and by flow cytometry after propidium iodide staining, as well as by biochemical criteria with the detection of DNA ladders after glucocorticoid treatment. The morphological and biochemical features observed in treated axolotls are in accordance with the criteria of apoptosis found in different models of mammalian lymphocyte programmed cell death. The onset of natural apoptosis was then detected by DNA fragmentation in thymus and in spleen during lymphocyte development and ontogenesis. A typical DNA ladder characteristic of apoptosis is detectable in the thymus as early as 5 …
Involvement of NO in contact hypersensitivity.
1998
The NO synthases (NOS) generate NO from L-arginine. High concentrations of NO have been shown to be responsible for tissue injury and cell death, while low concentrations of NO induce vasodilatation and other signaling effects. We have investigated the involvement of NO in contact hypersensitivity (CHS) reactions. CHS induced by treatment of BALB/c mice with the contact allergen 2,4-dinitrofluorobenzene (DNFB) was significantly reduced by the NOS inhibitor N-methyl-L-arginine (L-NMA), but not by the stereoisomer D-NMA, as shown by reduced ear swelling responses and evaluation of ear tissue sections. The CHS response was also reduced by aminoguanidine, which is known to preferentially inhibi…
Apoptosis of T cells and the control of inflammatory bowel disease: therapeutic implications.
2007
Inflammatory bowel diseases (IBDs) such as Crohn’s disease and ulcerative colitis are the result of an imbalanced mucosal T cell response. Despite the identification of a genetic susceptibility region in the NOD2/CARD15 (nucleotide-binding oligomerisation domain 2/caspase recruitment domain 15) gene, the aetiology is still unclear. Thus, the hunt for disease-initiating factors such as defects in the mucosal barrier or pathogenic microorganisms is ongoing. By contrast, the immunopathogenesis in IBDs is better understood. The identification of cytokines that are involved in T cell and monocyte signalling led to specific therapeutic concepts. Recent data have clearly shown that the most powerf…
Selective targeting of activated T cells in chronic intestinal inflammation
2009
Programmed cell death (apoptosis) has been implicated in normal biological processes as well as in the pathology of human diseases.1 The characterisation of genes involved in apoptosis has been pursued intensively and led to the identification of two major classes of genes: the bcl-2 family and the caspase family. Caspases are proteases that cleave their target substrates at specific peptide sequences and during apoptosis the activation of caspases takes place in a cascade fashion, leading to nuclear engulfment and cell death. Thus, caspases represent key functional components of the apoptosis pathway in human cells. Resistance against apoptosis is a key phenomenon in various chronic inflam…
Processing without proteolytic cleavage is required for recognition of insulin by T cells.
1990
Beef insulin as well as a chymotryptic A-chain fragment [BI-A1-14(SSO3-)3] need uptake by antigen-presenting cells (APC) for efficient presentation in combination with major histocompatibility complex class II molecules to insulin-specific T cells. This could be shown by the inability of aldehyde-fixed APC to present these antigens to T cells. Furthermore, presentation of the insulin fragment as well as presentation of ovalbumin (OVA) was inhibited by treatment of APC with chloroquine, cerulenin or tunicamycin. This was not the case for a processing-independent OVA peptide. Treatment of APC during antigen pulsing with various protease inhibitors, active on all classes of proteases, did not …