Search results for "lymphocyte activation"
showing 10 items of 414 documents
Non-eosinophilic Airway Hyper-reactivity in Mice, Induced by IFN-γProducing CD4+and CD8+Lung T cells, is Responsive to Steroid Treatment
2014
Non-eosinophilic asthma is characterized by infiltration of neutrophils into the lung and variable responsiveness to glucocorticoids. The pathophysiological mechanisms have not been characterized in detail. Here, we present an experimental asthma model in mice associated with non-eosinophilic airway inflammation and airway hyper-responsiveness (AHR). For this, BALB/c mice were sensitized by biolistic DNA immunization with a plasmid encoding the model antigen β-galactosidase (pFascin-βGal mice). For comparison, eosinophilic airway inflammation was induced by subcutaneous injection of βGal protein (βGal mice). Intranasal challenge of mice in both groups induced AHR to a comparable extent as w…
Systematic review: progression of beryllium sensitization to chronic beryllium disease
2012
BACKGROUND The relevance of beryllium sensitization testing for occupational health practice and prevention is unclear. AIMS To analyse the natural course of beryllium sensitization and clarify the prognosis following cessation of exposure among sensitized workers. METHODS An electronic literature search was conducted in PubMed, Embase, Toxline and Cochrane databases supplemented by a manual search. Data abstraction and study quality assessment with adapted guideline checklists were performed independently by three reviewers. Seven studies met the eligibility criteria and were included in the systematic review; however, six of the seven studies were of low methodological quality. RESULTS A …
IL-10 down-regulates T cell activation by antigen-presenting liver sinusoidal endothelial cells through decreased antigen uptake via the mannose rece…
1998
SUMMARYOur study demonstrates that antigen-presenting liver sinusoidal endothelial cells (LSEC) induce production of interferon-gamma (IFN-γ) from cloned Th1 CD4+ T cells. We show that LSEC used the mannose receptor for antigen uptake, which further strengthened the role of LSEC as antigen-presenting cell (APC) population in the liver. The ability of LSEC to activate cloned CD4+ T cells antigen-specifically was down-regulated by exogenous prostaglandin E2 (PGE2) and by IL-10. We identify two separate mechanisms by which IL-10 down-regulated T cell activation through LSEC. IL-10 decreased the constitutive surface expression of MHC class II as well as of the accessory molecules CD80 and CD86 …
Peptide Processing Is Critical for T-Cell Memory Inflation and May Be Optimized to Improve Immune Protection by CMV-Based Vaccine Vectors.
2016
Cytomegalovirus (CMV) elicits long-term T-cell immunity of unparalleled strength, which has allowed the development of highly protective CMV-based vaccine vectors. Counterintuitively, experimental vaccines encoding a single MHC-I restricted epitope offered better immune protection than those expressing entire proteins, including the same epitope. To clarify this conundrum, we generated recombinant murine CMVs (MCMVs) encoding well-characterized MHC-I epitopes at different positions within viral genes and observed strong immune responses and protection against viruses and tumor growth when the epitopes were expressed at the protein C-terminus. We used the M45-encoded conventional epitope HGI…
The effect of age on mitogen responsive T cell precursors in human beings is completely restored by interleukin-2.
1992
Abstract It is well known that the function of T lymphocytes is significantly impaired by advancing age. In the present study, attempts have been made to further characterize the T cell impairment of elderly subjects. Thus, we have performed limiting dilution microculture analysis to evaluate the precursor frequency of T lymphocytes responding to a mitogenic stimulus in old and young subjects. Furthermore we have evaluated the activity of recombinant interleukin-2 (rIL-2) on these cells. The results demonstrate that in older subjects the frequency of these precursors is significantly decreased. The in vitro treatment with rIL-2 increased the frequency of mitogen responsive T lymphocyte prec…
Alternative Polyadenylation Events Contribute to the Induction of NF-ATc in Effector T Cells
1999
Abstract The transcription factor NF-ATc is synthesized in three prominent isoforms. These differ in the length of their C terminal peptides and mode of synthesis. Due to a switch from the use of a 3′ polyA site to a more proximal polyA site, NF-ATc expression switches from the synthesis of the two longer isoforms in naive T cells to that of short isoform A in T effector cells. The relative low binding affinity of cleavage stimulation factor CstF-64 to the proximal polyA site seems to contribute to its neglect in naive T cells. These alternative polyadenylation events ensure the rapid accumulation of high concentrations of NF-ATc necessary to exceed critical threshold levels of NF-ATc for g…
A novel B cell population revealed by a CD38/CD24 gating strategy: CD38−CD24− B cells in centenarian offspring and elderly people
2012
The B cell arm of adaptive immunity undergoes significant modifications with age. Elderly people are characterized by impaired B cell responses reflected in a reduced ability to effectively respond against viruses and bacteria. Alterations of immunity with advancing age (immunosenescence) have been widely studied in centenarians who are considered a good example of successful aging. In recent years, attention has shifted to centenarian offspring (CO) as a model of people genetically advantaged for healthy aging and longevity. Here, we describe the preliminary characterization of a proposed new population of memory B cells, defined as CD19(+)CD38(-)CD24(-), which we find at higher frequencie…
Interferon-α Suppresses cAMP to Disarm Human Regulatory T Cells
2013
Abstract IFN-α is an antineoplastic agent in the treatment of several solid and hematologic malignancies that exerts strong immune- and autoimmune-stimulating activity. However, the mechanisms of immune activation by IFN-α remain incompletely understood, particularly with regard to CD4+CD25highFoxp+ regulatory T cells (Treg). Here, we show that IFN-α deactivates the suppressive function of human Treg by downregulating their intracellular cAMP level. IFN-α–mediated Treg inactivation increased CD4+ effector T-cell activation and natural killer cell tumor cytotoxicity. Mechanistically, repression of cAMP in Treg was caused by IFN-α–induced MAP–ERK kinase (MEK)/extracellular signal-regulated ki…
Analysis of nucleophosmin–anaplastic lymphoma kinase (NPM‐ALK)‐reactive CD8+ T cell responses in children with NPM‐ALK+ anaplastic large cell lymphoma
2016
Summary Cellular immune responses against the oncoantigen anaplastic lymphoma kinase (ALK) in patients with ALK-positive anaplastic large cell lymphoma (ALCL) have been detected using peptide-based approaches in individuals preselected for human leucocyte antigen (HLA)-A*02:01. In this study, we aimed to evaluate nucleophosmin (NPM)-ALK-specific CD8+ T cell responses in ALCL patients ensuring endogenous peptide processing of ALK antigens and avoiding HLA preselection. We also examined the HLA class I restriction of ALK-specific CD8+ T cells. Autologous dendritic cells (DCs) transfected with in-vitro-transcribed RNA (IVT-RNA) encoding NPM–ALK were used as antigen-presenting cells for T cell …
Hepatitis B surface antigen presentation and HLA-DRB1*– lessons from twins and peptide binding studies
2005
Summary The aim of this study was to investigate the underlying mechanisms of the genetic association between certain HLA-DRB1* alleles and the immune response to HBsAg vaccination. Therefore, HBsAg peptide binding to HLA-DR molecules was measured in vitro by peptide binding ELISAs. Additionally, HBsAg-specific T cell reaction and cytokine profile of immune response were analysed ex vivo in ELISPOT assays and DR-restriction of T-cell proliferative responses was investigated with HBsAg specific T cell clones. In addition, we compared HBsAg specific T cell responses of 24 monozygotic and 3 dizygotic twin pairs after HBsAg vaccination. Our results showed that the peptide binding assays did not…