title: CD8+ T-cell interaction with HCV replicon cells: evidence for both cytokine- and cell-mediated antiviral activity.
abstract: The interaction between the host immune response and infected hepatocytes plays a central role in the pathogenesis of hepatitis C virus (HCV). The lack of a suitable animal or in vitro model has hindered our understanding of the host T-cell/HCV interaction. Our aim was to develop an in vitro model to study the mechanisms of HCV-specific T-cell-mediated antiviral and cytolytic function. The HCV replicon was HLA typed and lymphocytes were obtained from an HLA class I-matched subject. CD8(+) T cells were expanded with 2 HCV-specific/HLA-restricted peptides for NS3. Lymphocyte preparations were cocultured with HCV replicon (FCA1) and control (Huh7) cells labeled with (51)Cr. After a 48-hour incubation, the cells were harvested for RNA extraction. Standard blocking assays were performed in the presence of anti-interferon gamma (IFN-gamma), anti-tumor necrosis factor alpha (TNF-alpha), and anti-FasL. Cytolytic activity was measured by (51)Cr release. HCV replicon cells express homozygous HLA-A11 alleles and present HCV nonstructural proteins. HCV-specific expansion of CD8(+) cells led to a 10-fold decrease in HCV replication by Northern blot analysis and 21% specific lysis of FCA1 cells (compared with 2% of control Huh7 cells). Twenty percent of this antiviral activity was independent of T-cell binding, suggesting cytokine-mediated antiviral activity. The CD8(+) antiviral effect was markedly reduced by blocking either IFN-gamma or FasL but was unaffected by blocking TNF-alpha. In conclusion, HCV-specific CD8(+) cells inhibit viral RNA replication by cytokine-mediated and direct cytolytic effects. This T-cell/HCV subgenomic replicon system represents a model for the investigation of CD8 cell interaction with HCV-infected hepatocytes.
authors.affiliation: Department of Pathology, Immunology, and Laboratory Medicine, University of Florida, Gainesville, FL, USA.
authors.forename: Chen
authors.initials: C
authors.lastname: Liu
authors.forename: Haizhen
authors.initials: H
authors.lastname: Zhu
authors.forename: Zhengkun
authors.initials: Z
authors.lastname: Tu
authors.forename: Yi-Ling
authors.initials: YL
authors.lastname: Xu
authors.forename: David R
authors.initials: DR
authors.lastname: Nelson
mesh_terms: D000906:Antibodies / Q000494:pharmacology; D000914:Antibodies, Viral / Q000276:immunology; D000917:Antibody Formation; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology / Q000502:physiology*; D002450:Cell Communication; D016207:Cytokines / Q000502:physiology*; D053222:Fas Ligand Protein; D006680:HLA Antigens / Q000032:analysis / Q000378:metabolism; D016174:Hepacivirus / Q000235:genetics / Q000276:immunology / Q000502:physiology*; D006801:Humans; D007371:Interferon-gamma / Q000276:immunology; D008099:Liver; D008198:Lymph Nodes / Q000166:cytology; D008562:Membrane Glycoproteins / Q000276:immunology; D012093:Replicon; D014407:Tumor Cells, Cultured; D014409:Tumor Necrosis Factor-alpha / Q000276:immunology
chemical_list: D000906:Antibodies; D000914:Antibodies, Viral; D016207:Cytokines; C505661:FASLG protein, human; D053222:Fas Ligand Protein; D006680:HLA Antigens; D008562:Membrane Glycoproteins; D014409:Tumor Necrosis Factor-alpha; D007371:Interferon-gamma