title: Impaired effector function of hepatitis C virus-specific CD8+ T cells in chronic hepatitis C virus infection.
abstract: The cellular immune response contributes to clearance of hepatitis C virus (HCV) and persists for decades after recovery from infection. The immunological basis for the inefficiency of the cellular immune response in chronically infected persons is not known. Here, we used four HLA-A2 tetramers, specific for two HCV core and two HCV NS3 epitopes, to investigate at the single-cell level effector function and phenotype of HCV-specific CD8+ T cells in 20 chronically infected and 12 long-term recovered patients. Overall, HCV-specific, tetramer+ T cells were more frequently found in PBMCs of chronically infected patients than in those of recovered patients. However, when compared with HCV-tetramer+ T cells of recovered patients, they displayed an impaired proliferative capacity. As a result of the impaired proliferative capacity, HCV-specific T cell lines derived from chronically infected patients displayed less peptide-specific cytotoxicity than those from recovered patients. In addition, proliferation and ex vivo IFN-gamma production of HCV-tetramer+ cells, but not influenza-virus-specific T cells, were defective in chronically infected patients and could not be restored by in vitro stimulation with peptide and IL-2. At least three distinct phenotypes of HCV-specific CD8+ T cells were identified and associated with certain functional characteristics. In addition, impairment of proliferative, cytokine, and cytotoxic effector functions of tetramer+ T cells in viremic patients was associated with weak ex vivo HCV-specific CD4+ T cell responses. Thus, the defective functions of HCV-specific CD8+ T cells might contribute to viral persistence in chronically infected patients, and knowledge on their reversibility may facilitate the development of immunotherapeutic vaccines.
authors.affiliation: Liver Diseases Section, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA.
authors.forename: Heiner
authors.initials: H
authors.lastname: Wedemeyer
authors.forename: Xiao-Song
authors.initials: XS
authors.lastname: He
authors.forename: Michelina
authors.initials: M
authors.lastname: Nascimbeni
authors.forename: Anthony R
authors.initials: AR
authors.lastname: Davis
authors.forename: Harry B
authors.initials: HB
authors.lastname: Greenberg
authors.forename: Jay H
authors.initials: JH
authors.lastname: Hoofnagle
authors.forename: T Jake
authors.initials: TJ
authors.lastname: Liang
authors.forename: Harvey
authors.initials: H
authors.lastname: Alter
authors.forename: Barbara
authors.initials: B
authors.lastname: Rehermann
mesh_terms: D000328:Adult; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology / Q000378:metabolism / Q000821:virology; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology* / Q000378:metabolism / Q000821:virology*; D002460:Cell Line; D003601:Cytotoxicity Tests, Immunologic; D018984:Epitopes, T-Lymphocyte / Q000097:blood / Q000276:immunology*; D005260:Female; D016174:Hepacivirus / Q000276:immunology*; D019698:Hepatitis C, Chronic / Q000276:immunology* / Q000821:virology*; D006801:Humans; D016130:Immunophenotyping; D007371:Interferon-gamma / Q000096:biosynthesis; D008213:Lymphocyte Activation; D018655:Lymphocyte Count; D008297:Male; D008875:Middle Aged; D016176:T-Lymphocyte Subsets / Q000276:immunology / Q000378:metabolism / Q000821:virology; D014758:Viral Core Proteins / Q000276:immunology; D017361:Viral Nonstructural Proteins / Q000276:immunology; D012697:Serine Endopeptidases; D043583:Nucleoside-Triphosphatase; D053487:DEAD-box RNA Helicases; D000085242:Viral Proteases
chemical_list: D018984:Epitopes, T-Lymphocyte; D007371:Interferon-gamma; D014758:Viral Core Proteins; D017361:Viral Nonstructural Proteins; C084422:NS3 protein, hepatitis C virus; D012697:Serine Endopeptidases; D043583:Nucleoside-Triphosphatase; D053487:DEAD-box RNA Helicases; D000085242:Viral Proteases