Search results for " ACTIVATION"
showing 10 items of 1535 documents
Induction of the anti-ergotypic response.
1993
The injection of syngeneic activated T cells into rodents can induce a T cell response against activation markers of the T cells, ergotopes. The responding anti-ergotypic T cells have been shown to suppress experimental autoimmune encephalomyelitis (EAE). This paper reports the characteristics of the anti-ergotypic response. It was found that irradiated activated T cells were as good as untreated living activated T cells in inducing anti-ergotypic cells in vivo. Glutardialdehyde-fixed (0.3%) cells were poor stimulators in vivo and non-stimulatory in vitro. Dilution of glutardialdehyde to 0.003% before fixation preserved the stimulatory capacity in vitro. Fixation or irradiation of T cells a…
Genetic proof for the transient nature of the Th17 phenotype
2010
IL-17-producing CD4(+) T cells (Th17) have been classified as a new T helper cell subset. Using an IL-17 fate mapping mouse strain, which genetically fixes the memory of IL-17 expression, we demonstrate that IL-17A/F-expressing T helper cells generated either in vitro or in vivo are not a stable T-cell subset. Upon adoptive transfer of IL-17F-reporter-positive Th17 cells to RAG-deficient or WT animals, encephalitogenic Th17 cells partially lose IL-17 expression and upregulate IFN-γ. Additionally, we show that Th1 cells can convert in vivo to IL-17A/IFN-γ-coexpressing cells in the mesenteric lymph nodes (mLN). Our data classify IL-17A and IL-17F as cytokines produced transiently in response …
Cytomegalovirus Misleads Its Host by Priming of CD8 T Cells Specific for an Epitope Not Presented in Infected Tissues
2003
Cytomegaloviruses (CMVs) code for several proteins that inhibit the presentation of antigenic peptides to CD8 T cells. Although the molecular mechanisms of CMV interference with the major histocompatibility complex class I pathway are long understood, surprisingly little evidence exists to support a role in vivo. Here we document the first example of the presentation of an antigenic peptide being blocked by a CMV immune evasion protein in organs relevant to CMV disease. Although this Db-restricted peptide, which is derived from the antiapoptotic protein M45 of murine CMV (mCMV), is classified as an immunodominant peptide based on response magnitude and long-term memory, adoptive transfer of…
Therapeutic Vaccination of Hematopoietic Cell Transplantation Recipients Improves Protective CD8 T-Cell Immunotherapy of Cytomegalovirus Infection
2021
Reactivation of latent cytomegalovirus (CMV) endangers the therapeutic success of hematopoietic cell transplantation (HCT) in tumor patients due to cytopathogenic virus spread that leads to organ manifestations of CMV disease, to interstitial pneumonia in particular. In cases of virus variants that are refractory to standard antiviral pharmacotherapy, immunotherapy by adoptive cell transfer (ACT) of virus-specific CD8+ T cells is the last resort to bridge the “protection gap” between hematoablative conditioning for HCT and endogenous reconstitution of antiviral immunity. We have used the well-established mouse model of CD8+ T-cell immunotherapy by ACT in a setting of experimental HCT and mu…
TH17 cells mediate pulmonary collateral priming
2010
Background Our laboratory has shown that inhalational sensitization to new antigens is facilitated through an ongoing T H 2-polarized inflammation of the lung, a phenomenon we call "collateral priming." Objective We were interested to analyze whether a T H 1-polarized pulmonary inflammation also facilitates priming toward new antigens and which cytokine or cytokines are involved. Methods T H 1-polarized T cells were generated in vitro and transferred into congenic mice. Mice were challenged initially with cognate antigen and an unrelated antigen; consecutively, they received cognate antigen or the secondary antigen. Airway inflammation, antigen-specific IgG2a levels, and airway hyperrespons…
B?cells are not required for T?cell priming in low zone tolerance to contact allergens and contact hypersensitivity
2004
Low zone tolerance (LZT) to contact allergens is induced by epicutaneous exposure to haptens in subsensitizing doses resulting in an inhibition of contact hypersensitivity (CHS), which, in contrast, occurs after sensitization with immunogenic doses of allergens. Performing the protocol of tolerance induction resulted in robust LZT to allergens in B cell-deficient mice in vivo, indicating that B cells are not required for the induction and effector phase of LZT. However, CHS reactions in vivo were restricted in B cell-deficient mice as compared to wild-type (WT) mice. In contrast, analysis of hapten-specific T cell activation in vitro revealed a strong proliferative response of T cells deriv…
B cell immunosenescence: different features of naive and memory B cells in elderly.
2011
Elderly people show a reduced protection against new infections and a decreased response to vaccines as a consequence of impairment of both cellular and humoral immunity. In this paper we have studied memory/naive B cells in the elderly, evaluating surface immunoglobulin expression, production of the pro- and anti-inflammatory cytokines, tumor necrosis factor (TNF)-α and interleukin (IL)-10, and presence of somatic hypermutation, focusing on the IgG(+)IgD(-)CD27(-) double negative (DN) B cells that are expanded in the elderly. Our results show that naive B cells from young donors need a sufficiently strong stimulus to be activated "in vitro", while naive B cells from old subjects are able t…
β-Adrenoceptor stimulation up-regulates phosphodiesterase 4 activity and reduces prostaglandin E 2 -inhibitory effects in human neutrophils
2000
Human neutrophils were treated for 4 h with a combination of salbutamol (1 µM), a β2-adrenoceptor agonist, and rolipram (30 µM), a selective phosphodiesterase 4 inhibitor, to investigate whether this treatment produces up-regulation of phosphodiesterase activity with functional consequences. Anion-exchange chromatography coupled with the use of selective activators and inhibitors demonstrated that a phosphodiesterase activity with characteristics of the isoenzyme type 4 was increased in drug-treated cells. Kinetic analysis showed a ~1.5-fold increase in V max without alteration of K m values. The augmented phosphodiesterase activity in drug-treated cells was abolished by actinomycin D. Cycl…
Study of T-cell activation in Type I diabetic patients and pre-Type I diabetic subjects by cytometric analysis: Antigen expression defectin vitro
1993
In Type I diabetes the observation of a decreased release of interleukin-2 (IL-2) and soluble IL-2 receptors by means of stimulated lymphocytes in vitro indicates that a primary immunoregulatory defect may be involved. To confirm this hypothesis we investigated the T-cell activation trend, evaluating the surface expression of IL-2 receptor (CD25), transferrin (CD71), HLA class II (DR), and CD69 phenotypes after in vitro stimulation with phytohemagglutinin (PHA; 1 and 10 micrograms/ml) and concanavalin A (12.5 micrograms/ml) in six newly diagnosed Type I diabetics and six islet cell- and insulin autoantibody-positive first-degree relatives. As controls were studied six long-standing Type I d…
T-cell activation in HLA-B8,DR3-positive individuals early antigen expression defect in vitro
1995
The HLA-B8, DR3 haplotype is overrepresented in several autoimmune diseases, implying that genes predisposing to these disorders are linked to this haplotype. In the patients affected by these diseases, as well as in healthy HLA-B8, DR3 individuals, various dysfunctions reflecting an impairment of T-cell activation have been found. To better characterize T-cell impairment of HLA-B8, DR3-positive healthy individuals, we analyzed the surface expression of early (CD69) and late (CD71) activation phenotypes. MNC cultures were stimulated with PHA and used for T-cell phenotyping by flow cytometry analysis. The results showed that the percentage of CD69+ T cells was significantly decreased in MNC …