Liver-Derived Hepatitis C Virus (HCV)-Specific CD4+ T Cells Recognize Multiple HCV Epitopes and Produce Interferon Gamma



Virus-specific CD4+ T-cell response at the site of inflammation is believed to play a decisive role for the course of viral disease. In hepatitis C virus (HCV) infection, the majority of studies focused on the peripheral blood T-cell response. In this study we analyzed intrahepatic virus-specific CD4+ T-cell response and compared this with that in the peripheral blood. Liver and blood-derived T-cell lines were studied in 36 patients (18 with chronic hepatitis C and 18 with HCV-associated cirrhosis). Virus-specific interferon gamma (IFN-γ) production at a single cell level to various HCV-proteins (core, nonstructural [NS] 3/4, NS5) were determined by enzyme-linked immunospot (ELIspot). Phenotyping was done by fluorescent-activated cell sorter analysis. In approximately half (16 of 36 [44%]) of intrahepatic T-cell lines a significant number of IFN-γ spots were observed, whereas this was the case in only 19% (7 of 36 T-cell lines) in the blood. In relative terms, core and nonstructural proteins were recognized with the same frequency in both compartments, but HCV-specificity was significantly more often detected in liver tissue compared with the blood. Hepatitis activity index, viral load, and alanine transaminase levels did not correlate with the detection of HCV-specific CD4+ T cells. All T-cell lines were dominated by CD4+ T cells. In conclusion, HCV-specific CD4+ T cells are multispecific, compartmentalize to the liver, and produce IFN-γ. We speculate that our data would support the concept of compartmentalization of specific T cells at the site of inflammation and that a low frequency of specific T cells is associated with failure to clear the virus and a chronic course of disease.