CD8+ CTL (cd8+ + ctl)

Distribution by Scientific Domains


Selected Abstracts


DNA vaccine encoding endosome-targeted human papillomavirus type,16 E7,protein generates CD4+ T cell-dependent protection

EUROPEAN JOURNAL OF IMMUNOLOGY, Issue 2 2007
Jean-Marc Brulet
Abstract Human papillomavirus type,16 is commonly implicated in cervical cancers. The viral genome encodes potential targets like the oncoprotein,E7, expressed in transformed cells but thought to represent a poorly immunogenic antigen. We describe in this work a DNA-based vaccination protocol aimed at inducing an efficient anti-E7 immune response in vivo. Plasmids allowing the expression of the E7,protein in distinct cellular compartments were generated and assayed in an in vivo model of tumor growth. Our data demonstrate that mice vaccinated with a plasmid encoding for an E7,protein fused to a domain of the MHC class,II-associated invariant chain (IiE7) were protected against tumor challenge. Mice immunized against an ubiquitinated form of E7 (Ub(Ala)E7) failed to control tumor growth. Protection induced by IiE7 was correlated with the development of CD8+ CTL and required the presence of CD4+ cells. In vitro studies confirmed that the IiE7 fusion protein was expressed at high levels in the endosomal compartment of transfected cells, while the natural and the ubiquitin-modified form of E7 were mainly nuclear. The present study suggests that an efficient anti-tumor response can be induced in vivo by DNA constructs encoding for E7,protein forms localizing at the endosomal compartment. See accompanying commentary: http://dx.doi.org/10.1002/eji.200636233 [source]


Increased natural cytotoxicity receptor expression and relevant IL-10 production in NK cells from chronically infected viremic HCV patients

EUROPEAN JOURNAL OF IMMUNOLOGY, Issue 2 2007
Andrea De Maria M. D.
Abstract Hepatitis C virus (HCV) readily establishes high-level lifelong persistent infection in the majority of immunocompetent adults with failure of HCV-specific CD8+ CTL to clear viral replication. Virus-induced conditioning of innate immune responses is a possible mechanism that may contribute to the impairment of virus-specific CD8+ CTL responses. Here, we analyzed whether triggering of NK cell receptor expression and function is affected during chronic viremic HCV infection. Flow cytometric analysis of purified resting peripheral NK cells showed no evidence of NK cell activation, while analysis of natural cytotoxicity receptors (NCR) showed that NK cells from HCV-infected patients had selective increased expression of NKp30 and NKp46. NK cells had corresponding conserved cytotoxic activity against all targets with the exception of HepG2 hepatoma cells. Freshly separated NK cells from HCV patients showed significant production of IL-10 and normal concentrations of IFN-, upon cell-mediated triggering. Thus, increased expression of NKp30 during HCV infection with increased IL-10 production could contribute, once NK cells localize in the liver, to a NK-DC crosstalk leading to skewing of subsequent adaptive immune responses and lack of virus control. [source]


Polymorphism in the proximal promoter region of the perforin gene and its impact on the course of HIV infection

INTERNATIONAL JOURNAL OF IMMUNOGENETICS, Issue 2 2006
D. McIlroy
Summary Cytotoxic T lymphocytes (CTLs) play an essential role in the control of viral replication during human immunodeficiency virus (HIV) infection. However, the efficacy of the CTL response varies between individuals. We tested the hypothesis that genetic polymorphisms in the lytic effector molecule perforin could influence the progression of HIV infection. The perforin gene was screened for single nucleotide polymorphisms (SNPs) by denaturing high-performance liquid chromatography (dHPLC). Correlations were sought between perforin genotype, perforin expression and lytic function of CD8+ T lymphocytes from HIV-positive patients. Association of perforin genotype with disease progression was investigated in 426 seroconverters enrolled in the French SEROCO cohort. AIDS-free survival curves were constructed using the Kaplan,Meier method and compared using the log-rank test. Three SNPs were found in the proximal promoter region of the perforin gene: 63G (allelic frequency 0.029), 112G (allelic frequency 0.071) and 1012T (allelic frequency 0.070). The presence of the 1012T genotype correlated with fewer perforin+ cells among circulating CD8+ CTL. However, CTL lines from HIV -positive individuals heterozygous for the perforin 1012T SNP displayed normal lysis of target cells, and within the SEROCO cohort, patients heterozygous for the 1012T SNP showed normal disease progression. However, 1012T/T homozygotes showed a tendency towards slower disease progression (P = 0.08). In conclusion, polymorphism in the perforin gene is limited, and although the 1012T genotype appears to influence perforin expression, it was not conclusively associated with disease progression in HIV infection. [source]


Genetic engineering of cytolytic T lymphocytes for adoptive T-cell therapy of neuroblastoma

THE JOURNAL OF GENE MEDICINE, Issue 6 2004
Sergio Gonzalez
Abstract Background Disease relapse is the leading cause of mortality for children diagnosed with disseminated neuroblastoma. The adoptive transfer of tumor-specific T cells is an attractive approach to target minimal residual disease following conventional therapies. We describe here the genetic engineering of human cytotoxic T lymphocytes (CTL) to express a chimeric immunoreceptor for re-directed HLA-independent recognition of neuroblastoma. Methods The CE7R chimeric immunoreceptor was constructed by PCR splice overlap extension and is composed of a single-chain antibody extracellular domain (scFv) derived from the L1-CAM-specific murine CE7 hybridoma fused to human IgG1 hinge-Fc, the transmembrane portion of human CD4, and the cytoplasmic tail of huCD3-, chain (scFvFc:,). Primary human T cells were genetically modified by naked DNA electrotransfer of plasmid expression vector CE7R-pMG then analyzed by Western blotting, flow cytometry for CE7R expression and cell surface trafficking, 4-h chromium release assay for re-directed neuroblastoma lysis, and ELISA for tumor-specific activation of cytokine production. Results CE7R is expressed as an intact chimeric protein that trafficks to the cell surface as a type I transmembrane protein. Primary human CE7R-expressing CD8+ CTL clones specifically recognize human neuroblastoma tumor cells and are activated for tumor cell lysis and Tc1 cytokine production. Conclusions These data demonstrate the utility of CE7R for re-directing the effector function of CTL to neuroblastoma and have provided the rationale to initiate a FDA-authorized (BB-IND#9149) pilot clinical trial to establish the feasibility and safety of adoptive transfer of autologous CE7R+CD8+ CTL clones to children with recurrent/refractory neuroblastoma. Copyright © 2004 John Wiley & Sons, Ltd. [source]


Successful In Vitro Priming of EBV-Specific CD8+ T Cells Endowed with Strong Cytotoxic Function from T Cells of EBV-Seronegative Children

AMERICAN JOURNAL OF TRANSPLANTATION, Issue 9 2006
P. Comoli
Epstein-Barr virus (EBV)-seronegative transplant recipients are at high risk of developing EBV-associated post-transplant lymphoproliferative disorder (PTLD), and would maximally benefit from an EBV-directed T-cell therapy for prevention or treatment of PTLD. So far, efforts to activate CD8+ EBV-specific cytotoxic T lymphocytes (CTL) endowed with high specific cytotoxicity from EBV-seronegative children have failed. We compared the CD8+ CTL priming efficiency of three different modified activation protocols, based on lymphoblastoid cell lines (LCL) stimulation potentially enhanced by either LCL presentation through dendritic cells, or selection of IFN-,+ cultured cells, or culture in the presence of rhIL-12 and rhIL-7, according to the standard protocol for reactivation of EBV-specific CTL. We found that only specific LCL stimulation in the presence of rhIL-12 and rhIL-7 was able to reproducibly expand EBV-specific CD8+ CTL endowed with strong cytotoxic activity from truly EBV-seronegative children. The lines thus activated, which included specificities toward EBV latent and lytic proteins, showed high percentage CD8+ T cells, with <10% naïve CD8+/CCR7+/CD45RA+ cells. Overall, the total number of CD8+ central memory cells, and of CCR7 T-cell effectors was comparable to that observed in healthy EBV-seropositive controls. In conclusion, it is feasible to activate EBV-specific CD8+ CTL with suitable characteristics for in vivo employment from EBV-seronegative children. [source]


Tetramer-blocking assay for defining antigen-specific cytotoxic T lymphocytes using peptide-MHC tetramer

CANCER SCIENCE, Issue 2 2006
Hiroshi Yokouchi
Peptide-MHC tetramers have been engineered to allow accurate detection of antigen-specific cytotoxic C lymphocytes (CTL) by flow cytometry. Here, we propose a novel use for peptide-MHC tetramers in the specific and sensitive analysis of the cytotoxic function of antigen-specific CTL by blocking MHC-restricted antigen-specific cytotoxicity. We found that pretreatment of ovalbumin (OVA)-specific CD8+ CTL (OT-1 CTL), derived from OT-1 T-cell receptor (TCR)-transgenic mice, with OVA257,264 peptide-H-2Kb tetramer caused a marked inhibition of the cytotoxicity against OVA-expressing EG-7 tumor cells. OVA257,264 peptide-H-2Kb tetramer did not block the cytotoxicity mediated by 2C mouse (H-2b)-derived CD8+ CTL, which recognize allo (H-2Ld) antigens. Moreover, OT-I CTL activity was not inhibited by an irrelevant HBV208,216 peptide-H-2Kb tetramer. These results indicate that the blocking of CTL activity with peptide-MHC tetramer was caused by interference with the interaction between the TCR and H-2Kb -OVA257,264 peptide complex, but not with the CD8-MHC class I interaction. The blocking activity of OVA257,264 peptide-H-2Kb tetramer was reversible because OT-I CTL pretreated with the tetramer recovered their cytotoxicity after culturing with interleukin-2 for 24 h. The same results were also demonstrated in freshly isolated, in vivo -primed OT-1 CTL sorted by the tetramer. These results demonstrate that peptide-MHC tetramer is a useful tool for defining MHC-restricted antigen-specific CTL function. Moreover, our finding implies that the measurement of CTL activity immediately after tetramer-guided sorting is not a suitable method for evaluating the function of in vivo -induced tetramer-positive CTL. We believe that the tetramer-blocking assay presented here will be useful for functionally monitor the induction of MHC-restricted antigen-specific CTL during vaccination therapy against tumor and infectious diseases. (Cancer Sci 2006; 97: 148 ,154) [source]


IL-10 down-regulates costimulatory molecules on Mycobacterium tuberculosis -pulsed macrophages and impairs the lytic activity of CD4 and CD8 CTL in tuberculosis patients

CLINICAL & EXPERIMENTAL IMMUNOLOGY, Issue 1 2004
S. DE LA BARRERA
SUMMARY Activation of T cells requires both TCR-specific ligation and costimulation through accessory molecules during T cell priming. IFN, is a key cytokine responsible for macrophage activation during Mycobacterium tuberculosis (Mtb) infection while IL-10 is associated with suppression of cell mediated immunity in intracellular infection. In this paper we evaluated the role of IFN, and IL-10 on the function of cytotoxic T cells (CTL) and on the modulation of costimulatory molecules in healthy controls and patients with active tuberculosis (TB). , -irradiated- Mtb (i- Mtb) induced IL-10 production from CD14+ cells from TB patients. Moreover, CD3+ T cells of patients with advanced disease also produced IL-10 after i- Mtb stimulation. In healthy donors, IL-10 decreased the lytic activity of CD4+ and CD8+ T cells whereas it increased ,, -mediated cytotoxicity. Furthermore, we found that the presence of IL-10 induced a loss of the alternative processing pathways of antigen presentation along with a down-regulation of the expression of costimulatory molecule expression on monocytes and macrophages from healthy individuals. Conversely, neutralization of endogenous IL-10 or addition of IFN, to either effector or target cells from TB patients induced a strong lytic activity mediated by CD8+ CTL together with an up-regulation of CD54 and CD86 expression on target cells. Moreover, we observed that macrophages from TB patients could use alternative pathways for i- Mtb presentation. Taken together, our results demonstrate that the presence of IL-10 during Mtb infection might contribute to mycobacteria persistence inside host macrophages through a mechanism that involved inhibition of MHC-restricted cytotoxicity against infected macrophages. [source]