Search results for " Immunologic"
showing 10 items of 538 documents
Cloning and expression of the complement receptor glycoprotein C from Herpesvirus simiae (herpes B virus): protection from complement-mediated cell l…
2003
Simian herpes B virus (SHBV) is the herpes simplex virus (HSV) homologue for the species MACACA: Unlike in its natural host, and unlike other animal herpesviruses, SHBV causes high mortality in accidentally infected humans. SHBV-infected cells, like those infected with HSV-1 and equine herpesvirus types 1 and 4, express complement C3 receptor activity. To study immunoregulatory functions involved in susceptibility/resistance against interspecies transmission, the SHBV glycoprotein C (gC(SHBV)) gene (encoding 467 aa) was isolated. Sequence analysis revealed amino acid identity with gC proteins from HSV-2 (46.9 %), HSV-1 (44.5 %) and pseudorabies virus (21.2 %). Highly conserved cysteine resi…
Combining dasatinib with dexamethasone long-term leads to maintenance of antiviral and antileukemia specific cytotoxic T cell responses in vitro
2012
Maintaining graft versus leukemia (GvL) and antivirus responses of cytotoxic T cells (CTLs) while suppressing graft-versus-host disease (GvHD) remains a challenge after allogeneic bone marrow transplantation. Clinical observations indicate that combining glucocorticoids with multi-tyrosine-kinase inhibitors could be a successful therapeutic approach. We and others have shown that the BCR-ABL/SRC kinase inhibitor dasatinib may enhance or suppress T cells in vitro. In this report, we evaluated combination effects of dasatinib and dexamethasone on CD3 + and virus-specific CD8 + T cells directly ex vivo and on antigen-specific leukemia-reactive and alloreactive CD8 + T cell clones. Functional o…
A tyrosinase peptide presented by HLA-B35 is recognized on a human melanoma by autologous cytotoxic T lymphocytes
1999
We previously described different cytotoxic T lymphocyte (CTL) clones isolated from the blood lymphocytes of a melanoma patient after in vitro stimulation with autologous tumor cells. These CTL clones recognized at least 2 distinct antigens on the melanoma cells. Here, we show that one of them consists of a peptide derived from tyrosinase and presented by HLA-B35. The peptide is 9 amino acids long and has the sequence LPSSADVEF. It can be presented by the 2 major B35 allelic subtypes, B*3501 and B*3503. As HLA-B35 is one of the most frequent HLA-B specificities, being present in about 20% of Caucasian individuals, it may be a useful target for peptide-based immunotherapy of melanoma.
Low frequency of cytotoxic liver-infiltrating T lymphocytes specific for endogenous processed surface and core proteins in chronic hepatitis B.
1993
To investigate the role of hepatitis B virus (HBV)-specific CD8+ T cells in chronic hepatitis B, the lytic activity of peripheral blood mononuclear cells (PBMC) and liver-infiltrating T cell clones and cytotoxic T cell (CTL) lines stimulated by recombinant vaccinia virus-infected cells were analyzed. Autologous and allogeneic Epstein-Barr virus-transformed B cells infected with vaccinia vectors (VAC) that contain sequences of the surface (S), secretory core (E), cytoplasmatic core (C) VAC antigen of HBV, or the wild-type (WT) VAC served as target cells. ELISA and immunoblotting showed HBV antigen expression in infected cells. Neither PBMC nor C- or E-VAC-stimulated CTL lines showed specific…
Dense Bodies of Human Cytomegalovirus Induce both Humoral and Cellular Immune Responses in the Absence of Viral Gene Expression
2000
ABSTRACTInfection of fibroblast cell cultures with human cytomegalovirus (HCMV) leads to the production of significant amounts of defective enveloped particles, termed dense bodies (DB). These noninfectious structures contain major antigenic determinants which are responsible for induction of both the humoral and the cellular immune response against HCMV. We tested the hypothesis that, by virtue of their unique antigenic and structural properties, DB could induce a significant immune response in the absence of infectious virus. Mice were immunized with gradient-purified DB, which were either left untreated or subjected to sequential rounds of sonication and freeze-thawing to prevent cellula…
Inhibition of the NKp30 activating receptor by pp65 of human cytomegalovirus.
2005
Human cytomegalovirus, a chief pathogen in immunocompromised people, can persist in a healthy immunocompetent host throughout life without being eliminated by the immune system. Here we show that pp65, the main tegument protein of human cytomegalovirus, inhibited natural killer cell cytotoxicity by an interaction with the activating receptor NKp30. This interaction was direct and specific, leading to dissociation of the linked CD3zeta from NKp30 and, consequently, to reduced killing. Thus, pp65 is a ligand for the NKp30 receptor and demonstrates a unique mechanism by which an intracellular viral protein causes general suppression of natural killer cell cytotoxicity by specific interaction w…
The use of HLA-A*0201-transfected K562 as standard antigen-presenting cells for CD8+ T lymphocytes in IFN-γ ELISPOT assays
2001
ELISPOT assays are increasingly used for a direct detection and quantification of single antigen-specific T cells in freshly isolated peripheral blood mononuclear cells (PBMC). They are particularly attractive for the monitoring of specific T lymphocyte responses in clinical trials assessing antigen-specific immunizations in patients with cancer or chronic viral infections. However, one major limitation for the broad clinical implementation of ELISPOT assays is the lack of an inexhaustible source of suitable HLA-matched antigen-presenting cells (APC). Currently available allogeneic or xenogeneic APC (such as the human lymphoid hybrid T2 or HLA-transfected insect cells) can either lead to st…
Upregulation of Major Histocompatibility Complex Class I on Liver Cells by Hepatitis C Virus Core Protein via p53 and TAP1 Impairs Natural Killer Cel…
2003
ABSTRACTThe mechanisms of immune evasion and the role of the early immune response in chronic infection caused by hepatitis C virus (HCV) are still unclear. Here, we present evidence for a cascade of molecular events that the virus initiates to subvert the innate immune attack. The HCV core protein induced p53-dependent gene expression of TAP1 (transporter associated with antigen processing 1) and consecutive major histocompatibility complex (MHC) class I upregulation. Moreover, in p53-deficient liver cell lines, only reconstitution with wild-type p53, but not mutated p53 lacking DNA binding capacity, showed this effect. As a consequence of increased MHC class I expression, a significantly …
Type I Interferon Protects Antiviral CD8+ T Cells from NK Cell Cytotoxicity
2014
Summary Despite development of new antiviral drugs, viral infections are still a major health problem. The most potent antiviral defense mechanism is the innate production of type I interferon (IFN-I), which not only limits virus replication but also promotes antiviral T cell immunity through mechanisms, which remain insufficiently studied. Using the murine lymphocytic choriomeningitis virus model system, we show here that IFN-I signaling on T cells prevented their rapid elimination in vivo. Microarray analyses uncovered that IFN-I triggered the expression of selected inhibitory NK-cell-receptor ligands. Consequently, T cell immunity of IFN-I receptor (IFNAR)-deficient T cells could be rest…
Impaired Mast Cell-Driven Immune Responses in Mice Lacking the Transcription Factor NFATc2
2009
Abstract The three calcium-dependent factors NFATc1, c2, and c3 are expressed in cells of the immune system and play pivotal roles in modulating cellular activation. With regard to NFATc2, it was reported that NFATc2-deficient mice display increased immune responses in several models for infection and allergy in vivo. This led to the assumption that NFATc2 is involved in the maintenance of immune homeostasis. Using the synthetic TLR7 agonist imiquimod as an adjuvant in epicutaneous peptide immunization, we observed that both the inflammatory reaction and the peptide-specific CTL response are severely impaired in NFATc2-deficient mice. Detailed analyses revealed that early production of proi…