Z Gastroenterol 2011; 49 - P4_42
DOI: 10.1055/s-0030-1269697

Ex vivo analysis of HCV-specific CD8+ T cell antiviral efficacy using a novel immunological model

B Seigel 1, B Bengsch 1, V Lohmann 2, HE Blum 1, R Thimme 1
  • 1Abt. Innere Medizin II, Medizinische Universitätsklinik Freiburg, Freiburg
  • 2Department of Molecular Virology, University of Heidelberg, Heidelberg

Virus-specific CD8+ T cells play an important role in the outcome (elimination versus persistence) and pathogenesis of hepatitis C virus (HCV) infection. Due to the lack of a suitable model, it is currently unclear whether and to what extent HCV-specific CD8+ T cells are able to exert direct antiviral efficacy. To address this important issue we utilized a novel immunological model based on a subgenomic HCV-replicating cell line stably transduced with the HLA-A2 gene (Huh7A2HCV) (Gastroenterology 2009). In this study, we compared the antiviral efficacy of HCV-specific CD8+ T cells to CMV-, EBV- and Flu-specific CD8+ T cells of the same patient. PBMCs from 15 chronically HCV infected patients were analyzed for virus-specific CD8+ T cells by tetramer staining and co-cultured with Huh7A2HCV cells pulsed with the respective peptides at a (E: T) ratio of 2: 1 for 72h. Inhibition of HCV RNA replication was measured by a decrease in luciferase activity.

Our results can be summarized as follows: First, co-culture of ex vivo-derived HCV-specific CD8+ T cells with the replicon cells resulted in an only minor inhibition of HCV replication (mean inhibition: ˜10%). Second, the specific dysfunction of HCV-specific CD8+ T cells was not dependent on the frequency of virus-specific CD8+ T cells but correlated with the expression of CD127 and PD-1. Third, in contrast to HCV-specific CD8+ T cells CMV-, EBV and Flu-specific CD8+ T cells were able to strongly inhibit viral replication after co-culture with Huh7A2HCV cells (mean inhibition: ˜75%). Fourth, the addition of selected cytokines (e.g. IL-2, IL-7 and IL-15) to the HCV-specific co-culture experiments resulted in an increase in HCV-specific CD8+ T cell antiviral efficacy.

In sum, these results demonstrate an impairment of antiviral efficacy of HCV-specific CD8+ T cells in chronic HCV infection that can be partially restored by the addition of cytokines like IL-2, IL-7 and IL-15.