Search results for " cytotoxic"
showing 10 items of 315 documents
MHC-unrestricted recognition of bacteria-infected target cells by human CD8+ cytotoxic T lymphocytes.
1992
Abstract A CD8 + αβTCR + T cell clone (A35) was isolated from the synovial fluid of a patient with postenteric reactive arthritis caused by Yersinia enterocolitica . This clone efficiently killed autologous and allogeneic target cells that had been preincubated with live but not with heat-killed bacteria. There was no restriction by polymorphic parts of HLA-A, -B. or -C molecules and a HLA class II-deficient mutant cell line was lysed as efficiently as its normal counterpart, whereas infected HLA class I-deficient cells (Daudi cells) were not. The clone showed crossreaction between Yersinia enterocolitica , Escherichia coli , Pseudomonas aeruginosa , and Streptococcus pyogenes , but did not…
Lysis of human melanoma cells by autologous cytolytic T cell clones. Identification of human histocompatibility leukocyte antigen A2 as a restriction…
1989
From the peripheral blood of the melanoma patient (AV), we derived cytolytic T lymphocyte (CTL) clones that lysed the autologous tumor line SK-MEL-29, but not autologous EBV-B cells, K562, and other tumor targets. By immunoselection experiments it was shown that the CTL clones recognized at least three different antigens on the autologous tumor cells. We demonstrate here that these melanoma antigens are presented to the CTL in association with HLA-A2. First, HLA-A2-reactive pregnancy sera as well as an mAb against HLA-A2 inhibited the CTL lysis. Second, immunoselected melanoma subclones that were resistant to lysis by CTL clones against the three antigens described were found to lack expres…
Cytolytic T-cell clones against an autologous human melanoma: specificity study and definition of three antigens by immunoselection.
1989
Cytolytic T-lymphocyte (CTL) clones against an autologous melanoma (SK-MEL-29) were generated by mixed lymphocyte tumor culture and subsequent cloning of responder lymphocytes at limiting dilutions. These CTL clones lysed autologous melanoma but not autologous Epstein-Barr virus-transformed B cells and none of the allogeneic tumor targets included in the specificity analysis. The lysis of autologous melanoma targets could be inhibited by monoclonal antibodies against monomorphic HLA class I determinants. For proliferation of CTLs, the stimulation with the relevant target antigen on autologous tumor cells was essential. Immunoselection experiments carried out with two CTL clones revealed the…
Assessment of the cytotoxic potential of an aqueous-ethanolic extract from Thalassia testudinum angiosperm marine grown in the Caribbean Sea
2018
Abstract Objectives Reported antioxidant, anti-inflammatory and neuroprotective properties for one aqueous-ethanolic extract from Thalassia testudinum which grows in the Caribbean Sea compelled us to explore about extract cytotoxic effects. Methods Cell viability was assayed on tumour (HepG2, PC12, Caco-2 and 4T1) and non-tumour (VERO, 3T3, CHO, MCDK and BHK2) cell lines. The extract effects upon primary cultures of rat and human hepatocytes and human lymphocytes were assayed. Key findings The extract exhibited cytotoxicity against cancer cells compared to normal cells, and the IC50 values were 102 μg/ml for HepG2, 135 μg/ml for PC12, 165 μg/ml for Caco-2 and 129 μg/ml for 4T1 cells after 4…
Quantitative and functional analysis of core-specific T-helper cell and CTL activities in acute and chronic hepatitis B
2008
Aims/background CD4+ T-helper cell (Th) responses to hepatitis B virus (HBV) core antigen (HBc) are increased during exacerbations in acute and chronic hepatitis B (AHB, CHB) and might influence the induction of CD8+ cytotoxic T lymphocytes (CTL) that are important for viral clearance. Methods HBc-specific proliferative responses and cytokine release of blood mononuclear cells (PBMC) were studied in patients with AHB or CHB, as well as responders and non-responders to interferon-alpha treatment (IFN-R, IFN-NR), by [3H]-thymidine-uptake, enzyme-linked immunosorbent assay (ELISA) and Elispot assay and were compared to peptide HBc18 27-specific CTL precursor frequencies among CD8+ T cells deri…
Association of T-cell regulatory gene polymorphisms with oral squamous cell carcinoma
2010
Costimulatory molecules have complementary effects on T-cell activation and their balance may control the development of oral cancer. The aim of this study was to determine the relevance of cytotoxic T-lymphocyte antigen 4 (CTLA-4), CD28 and inducible costimulator (ICOS) polymorphisms in oral squamous cell carcinoma (OSCC). Genotyping for CTLA-4 (-1661 A/G and +49 A/G), CD28 (0 C/G and +3160 G/T) and ICOS (+637 A/C and +1599 C/T) was performed in the 83 patients with OSCC, compared to the 40 unrelated healthy volunteers as controls. The genotype CTLA-4 -1661 was significantly different between the patient group and the control group. The allele CTLA-4 -1661 G was significantly found more fr…
Spontaneous and antibody-dependent cellular immune reactions to ethanol-altered hepatoma cells
2008
— Spontaneous cell-mediated cytotoxicity (SCMC), antibody-dependent cellular cytotoxicity (ADCC) and proliferative lymphocyte stimulation in alcoholic liver disease (ALD) were investigated. Peripheral blood lymphocytes (PBL) from eight patients with advanced ALD and nine normal controls were tested against hepatoma cells (PLC/PRF/5) as targets. Target cells were grown in either normal culture medium or medium supplemented with 1 and 5% ethanol, respectively, for 24 to 48 h. Ethanol-exposed hepatoma cells exhibited profound and characteristic morphological alterations. Ethanol preincubation, however, proved to be without effect on immune reactions. Provided that hepatoma cells are an appropr…
Peripheral blood dendritic cells are phenotypically and functionally intact in chronic hepatitis B virus (HBV) infection
2007
Summary Persistence of hepatitis B virus (HBV) infection is associated with reduced anti-viral T cell responses. Impaired dendritic cell (DC) function was suggested as the cause of reduced T cell stimulation in chronic HBV carriers. Thus, we compared myeloid (mDC) and plasmacytoid DC (pDC) from chronic HBV carriers and controls. Frequency and phenotype of isolated DC were analysed by fluorescence activated cell sorter staining, DC function by mixed lymphocyte reaction, cytokine bead array, intracellular cytokine staining, enzyme-linked immunosorbent assay and enzyme-linked immunospot. Expression of HBV DNA and mRNA was studied by polymerase chain reaction (PCR). Circulating total DC, mDC or…
Rare pre-core stop-codon mutant nt. 1897 predominates over wide-spread mutant nt. 1896 in an unusual course of chronic hepatitis B
1996
We present a patient with an unusual course of hepatitis B e antigen (HBeAg)-negative chronic hepatitis B who had repeated reactivations of his disease progressing to cirrhosis with terminal liver failure. Each flare up presented like an acute hepatitis with very high titres of hepatitis B virus (HBV) and high inflammatory activity followed by rapid clearance of viraemia. The pre-core genome of HBV isolated from sera during 5 years of follow up was analysed. Direct sequencing of polymerase chain reaction (PCR) products derived from consecutive sera showed a rare pre-core stop-codon mutation at nucleotide (nt.) 1897 G --> A with an accompanying mutation nt. 1857 C --> T as well as a stop-cod…
Partial and Ineffective Activation of Vγ9Vδ2 T Cells by Mycobacterium tuberculosis-Infected Dendritic Cells
2010
Abstract γδ T cells and dendritic cells (DCs) participate in early phases of immune response against Mycobacterium tuberculosis. We investigated whether a close functional relationship exists between these two cell populations using an in vitro coculture in a human system. Vγ9Vδ2 T cells induce full maturation of M. tuberculosis-infected immature DCs, as demonstrated by upregulation of the costimulatory CD80, CD86, CD40, and HLA-DR molecules on infected DCs after 24 h of coculture. Reciprocally, infected DCs induced substantial activation of Vγ9Vδ2 T cells upon coculture, which was cell-to-cell contact and TCR dependent, as demonstrated in transwell experiments. However, infected DCs select…