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Dysfunction and functional restoration of HCV-specific CD8 responses in chronic hepatitis C virus infection

Authors

  • Amalia Penna,

    Corresponding author
    1. Laboratory of Viral Immunopathology, Unit of Infectious Diseases and Hepatology, Azienda Ospedaliero-Universitaria di Parma, Parma, Italy
    • Laboratorio di Immunopatologia Virale-U.O., Malattie Infettive ed Epatologia, Azienda Ospedaliero-Universitaria di Parma, Via A. Gramsci, 14, 43100 Parma, Italy
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    • fax: (39) 0521-703857

  • Massimo Pilli,

    1. Laboratory of Viral Immunopathology, Unit of Infectious Diseases and Hepatology, Azienda Ospedaliero-Universitaria di Parma, Parma, Italy
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  • Alessandro Zerbini,

    1. Laboratory of Viral Immunopathology, Unit of Infectious Diseases and Hepatology, Azienda Ospedaliero-Universitaria di Parma, Parma, Italy
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  • Alessandra Orlandini,

    1. Laboratory of Viral Immunopathology, Unit of Infectious Diseases and Hepatology, Azienda Ospedaliero-Universitaria di Parma, Parma, Italy
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  • Sergio Mezzadri,

    1. Laboratory of Viral Immunopathology, Unit of Infectious Diseases and Hepatology, Azienda Ospedaliero-Universitaria di Parma, Parma, Italy
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  • Luca Sacchelli,

    1. Laboratory of Viral Immunopathology, Unit of Infectious Diseases and Hepatology, Azienda Ospedaliero-Universitaria di Parma, Parma, Italy
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  • Gabriele Missale,

    1. Laboratory of Viral Immunopathology, Unit of Infectious Diseases and Hepatology, Azienda Ospedaliero-Universitaria di Parma, Parma, Italy
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  • Carlo Ferrari

    1. Laboratory of Viral Immunopathology, Unit of Infectious Diseases and Hepatology, Azienda Ospedaliero-Universitaria di Parma, Parma, Italy
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  • Potential conflict of interest: Nothing to report.

Abstract

The functional impairment of HCV-specific T cell responses is believed to be an important determinant of HCV persistence, but the functional T cell defects of patients with chronic hepatitis C (CH-C) are only partially defined. CD8 responses to HLA-A2–restricted epitopes of HCV and other unrelated viruses were studied in 23 HLA-A2–positive patients both ex vivo and after in vitro culture. Degranulation capacity, intracellular perforin, and granzyme-A content and cytokine production (IFN-γ, TNF-α) by HCV- and non–HCV-specific CD8 cells were tested both ex vivo and in vitro, whereas cytolytic activity was studied after 10 days' expansion in vitro. Memory maturation and role of exhaustion were assessed ex vivo by HCV-specific CD8 staining for CD127 and PD-1, and in vitro after peripheral blood mononuclear cells (PBMC) culture in the presence of anti–PD-L1 monoclonal antibodies. IFN-γ production and cytolytic activity were expressed less efficiently by HCV-specific than by non–HCV specific CD8 cells derived from the same CH-C patients. The amount of stored granzyme-A within single cells was always lower in HCV-specific CD8 cells, which were less efficient also in the release of lytic granules and in the production of TNF-α. The CD8 dysfunction was associated with high PD-1 expression by most HCV-specific CD8 cells, and PD-1/PD-L1 blockade by anti–PD-L1 antibodies in vitro was able to improve the HCV-specific CD8 function. Conclusion: Our study characterizes CD8 defects that may be important in maintaining HCV persistence; identification of strategies to correct these defects may help to define novel approaches to treat HCV infection. (HEPATOLOGY 2007;45:588–601.)

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