Search results for " present"
showing 10 items of 566 documents
Presentation of an Immunodominant Immediate-Early CD8+ T Cell Epitope Resists Human Cytomegalovirus Immunoevasion.
2013
Control of human cytomegalovirus (HCMV) depends on CD8+ T cell responses that are shaped by an individual's repertoire of MHC molecules. MHC class I presentation is modulated by a set of HCMV-encoded proteins. Here we show that HCMV immunoevasins differentially impair T cell recognition of epitopes from the same viral antigen, immediate-early 1 (IE-1), that are presented by different MHC class I allotypes. In the presence of immunoevasins, HLA-A- and HLA-B-restricted T cell clones were ineffective, but HLA-C*0702-restricted T cell clones recognized and killed infected cells. Resistance of HLA-C*0702 to viral immunoevasins US2 and US11 was mediated by the alpha3 domain and C-terminal region …
The efficient bovine insulin presentation capacity of bone marrow-derived macrophages activated by granulocyte-macrophage colony-stimulating factor c…
1993
Bone marrow-derived macrophages (BMM phi) were shown before to function as antigen-presenting cells. We show here, that the antigen presentation capacity of BMM phi depends on the nature of the antigen and is differently regulated by the lymphokines interferon-gamma (IFN-gamma) and granulocyte/macrophage-colony-stimulating factor (GM-CSF). When bovine insulin (BI) was employed as antigen, only BMM phi treated with GM-CSF (GM-CSF-M phi) were efficient presenters, but when presentation of the antigens ovalbumin and conalbumin was tested, IFN-gamma-pulsed BMM phi (IFN-gamma-M phi) proved superior to GM-CSF-M phi. The lack of efficient BI presentation function of IFN-gamma-M phi was only obviou…
Generation of tumor-reactive CTL against the tumor-associated antigen HER2 using retrovirally transduced dendritic cells derived from CD34+ hemopoiet…
2000
Abstract Ag-specific CD8+ CTL are crucial for effective tumor rejection. Attempts to treat human malignancies by adoptive transfer of tumor-reactive CTL have been limited due to the difficulty of generating and expanding autologous CTL with defined Ag specificity. The current study examined whether human CTL can be generated against the tumor-associated Ag HER2 using autologous dendritic cells (DC) that had been genetically engineered to express HER2. DC progenitors were expanded by culturing CD34+ hemopoietic progenitor cells in the presence of the designer cytokine HyperIL-6. Proliferating precursor cells were infected by a retroviral vector encoding the HER2 Ag and further differentiated…
Consequences of antigen self-presentation by tumor-specific cytotoxic T cells.
2000
Abstract CDS-positive cytotoxic T cells (CTL) recognize antigenic peptides in combination with major histocompatibility complex (MHC) class I molecules on the surface of syngeneic antigen presenting cells (APC). In the present paper we show that cells from tumor antigen-specific CTL clones present their cognate antigenic peptide to other CTL from the same clone. Inter-CTL peptide presentation resulted in activation of the cells of one CTL clone to MHC-unrestricted lysis of bystander cells. In contrast to the behaviour of this clone, another CTL clone did not lyse bystander cells after incubation with the cognate peptide, but was activated to self-destruction. The human herpes virus Epstein-…
Cytotoxic T cells with reciprocal antigenic peptide presentation function are not generally resistant to mutual lysis
2003
Cytotoxic T cells normally express major histocompatibility complex class I molecules, to which their T cell antigen receptors are restricted. Therefore, a single cytotoxic T cell can not only act as a cytolytic effector cell, but also as an antigen-presenting cell for other cytotoxic T cells of the same or a different clone. In the present paper, we used a murine cytotoxic T cell clone, 10BK.1, recognizing the ovalbumin-derived peptide OVA257-264 in combination with H-2Kb to investigate the consequences of reciprocal antigen presentation by these cytotoxic T cells. These cells proliferate after incubation with the relevant peptide in the absence of added accessory cells, indicating recipro…
A continuous infusion of a minor histocompatibility antigen-immunodominant peptide induces a delay of male skin graft rejection.
2009
Abstract We previously reported that an inhibition of antigen-specific Interferon-γ release and cytotoxicity occurs after a continuous infusion of an HY immunodominant peptide although this treatment is not able to cause a significant delay of male skin grafts rejection. In vivo administration of high doses of an HY peptide, through mini-osmotic pumps, in naive female mice was used to study the effects on the male skin grafts rejection. A continuous infusion of 1 mg of an HY peptide induces a significant delay of male skin graft rejection. In vitro HY-specific Interferon-γ release was inhibited adding peptide-specific suppressor cells: the ability to inhibit Interferon-γ release was evident…
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.
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…
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 …