Expression of Hepatitis B Virus X Protein in Hepatocytes Suppresses CD8(+) T Cell Activity

BACKGROUND: CD8(+) T cells contribute to the clearance of Hepatitis B virus (HBV) infection and an insufficient CD8(+) T cell response may be one of the major factors leading to chronic HBV infection. Since the HBx antigen of HBV can up-regulate cellular expression of several immunomodulatory molecules, we hypothesized that HBx expression in hepatocytes might affect CD8(+) T cell activity. METHODS: We analyzed the activation and apoptosis of CD8(+) T cells co-cultured with primary hepatocytes rendered capable of expressing HBx by recombinant baculovirus infection. RESULTS: Expression of HBx in hepatocytes induced low production of interferon-γ and apoptosis of CD8(+) T cells, with no effect on CD8 T cell proliferation. However, transcriptional levels of H-2K, ICAM-1 and PD-1 ligand did not correlate with HBx expression in hepatocytes. CONCLUSION: Our results suggest that HBx may inhibit CD8(+) T cell response by regulation of interferon-γ production and apoptosis.