Search results for "T cell"
showing 10 items of 2228 documents
Mycobacterial antigen(s) induce anergy by altering TCR- and TCR/CD28-induced signalling events: insights into T-cell unresponsiveness in leprosy.
2009
Present study investigates the role of Mycobacterium leprae (M. leprae) antigens on TCR- and TCR/CD28-induced signalling leading to T-cell activation and further correlates these early biochemical events with T-cell anergy, as prevailed in advanced stages of leprosy. We observed that both whole cell lystae (WCL) and soluble fraction of M. leprae sonicate (MLSA) not only inhibited TCR, thapsigargin and ionomycin induced calcium fluxes by diminishing the opening of calcium channels, but also TCR- or TCR/CD28-induced proximal signalling events like phosphorylation of Zap-70 and protein kinase-C (PKC) activity. Study of TCR- and TCR/CD28-induced downstream signals revealed that M. leprae antige…
Overexpression of genes involved in lymphocyte activation and regulation are associated with reduced CRM-derived cardiac remodelling after STEMI
2021
Abstract Aims Lymphopenia after ST-segment elevation myocardial infarction (STEMI) correlates with deleterious cardiac consequences and worse prognosis. An in-depth examination of genes implicated in lymphocyte proliferation, activation and regulation and their association with short- and long-term cardiac structure and function is therefore of great interest. Methods Peripheral blood mononuclear cells were isolated from 10 control subjects and 64 patients with a first STEMI treated with primary percutaneous coronary intervention and submitted to cardiac magnetic resonance after 1 week and 6 months. mRNA expression of genes implicated in lymphocyte activation (CD25 and CD69) and regulation …
Selective depression of interferon-γ and granulysin production with increase of proliferative response by Vγ9/Vδ2 T cells in children with tuberculos…
2002
Vgamma9/Vdelta2 T cells can contribute to protective immune response against Mycobacterium tuberculosis, although the extent to which and mechanisms by which they could actually protect against human tuberculosis remain unclear. We have previously reported that Vgamma9/Vdelta2 T cells from tuberculin purified protein derivative (PPD)-positive children, either healthy or affected by different clinical forms of tuberculosis, strongly proliferate to different phosphoantigens in vitro, whereas Vgamma9/Vdelta2 T cells from PPD-negative healthy subjects proliferate very poorly. We report here that Vgamma9/Vdelta2 T cells from tuberculous children have an increased proliferative activity, but decr…
Decreased serum granulysin levels in childhood tuberculosis which reverse after therapy
2007
Abstract Granulysin is a cytolytic protein of natural killer (NK) cells and cytotoxic T lymphocytes (CTLs). Serum levels of granulysin are related to host cellular immunity. We used an ELISA to quantify granulysin serum levels in children with tuberculosis (TB), before and after chemotherapy. The study involved children affected by different clinical forms of TB (n=72) and healthy control children (n=150) from the same geographical area and of similar socio-economic background. Serum granulysin levels before the initiation of TB therapy were significantly lower in children with TB compared to controls, with the lowest levels being found in TB patients who were PPD skin test negative. No sta…
Inducible Co-Stimulator Null MRL-Fas lpr Mice
2005
MRL/MpJ-Tnfrsf6lpr (MRL-Faslpr) mice develop a spontaneous T cell-dependent autoimmune disease that shares features with human lupus, including fatal nephritis, systemic pathology, and autoantibodies (autoAb). The inducible co-stimulator (ICOS) is upregulated on activated T cells and modulates T cell-mediated responses. To investigate whether ICOS has an essential role in regulating autoimmune lupus nephritis and the systemic illness in MRL-Faslpr mice, ICOS null (-/-) MRL Faslpr and ICOS intact (+/+) MRL-Faslpr strains (wild-type [WT]) were generated and compared. It was determined that in ICOS-/- MRL-Faslpr as compared with the WT strain, (1) there is a significant reduction in circulatin…
Gamma delta T cells inhibit in vitro growth of the asexual blood stages of Plasmodium falciparum by a granule exocytosis-dependent cytotoxic pathway …
2004
Several reports have stated the ability of gamma delta T cells to inhibit the growth of the asexual blood stages of Plasmodium falciparum in vitro. However, little information is available about the mechanisms involved. In this study, in vitro systems were used to study the role of the granule exocytosis-dependent cytotoxic pathway in the growth inhibition/killing of P. falciparum by human gamma delta T cells. Our results show that the inhibition requires cell-to-cell contact and that gamma delta T cells kill the asexual blood stages of P. falciparum through a granule exocytosis-dependent cytotoxic pathway after recognition of certain ligands or molecules expressed on the surface of infecte…
Stimulator cell-dependent requirement for CD2- and LFA-1-mediated adhesions in T lymphocyte activation by superantigenic toxins.
1992
Abstract The staphylococcal enterotoxins and related microbial T cell mitogens stimulate T cells by cross-linking variable parts of the T cell receptor (TCR) with MHC class II molecules on accessory or target cells. We have used cloned human T cells and defined tumor cells as accessory cells (AC) to study the requirements for T cell activation by these toxins. On AC expressing high levels of CD54 (intercellular adhesion molecule-1, ICAM-1) and CD58 (lymphocyte function-associated antigen-3, LFA-3), mAb to CD2 were relatively ineffective in inhibiting the response to the toxins and antibodies to the lymphocyte function-associated antigen-1 (LFA-1) did not inhibit at all. If added together, h…
An antigen-independent physiological activation pathway for L3T4+ T lymphocytes.
1987
The data presented in this report describe an antigen-independent activation pathway leading to reinduction of proliferation of class II major histocompatibility complex (MHC)-restricted murine T cell lines that after previous antigen-specific stimulation reverted to a resting state. Antigen-independent proliferation and interleukin 2 (IL2)-receptor expression occur in the presence of splenic accessory cells, exogenous IL2 and a soluble factor(s) provisionally termed T cell-stimulating factor(s) (TSF). Each of these components is essential for inducing growth. TSF is found in the supernatant of an autoreactive T cell line upon stimulation with syngeneic accessory cells. Neither TSF nor acce…
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…