The role of hepatitis B virus-specific memory CD8 T cells in the control of viral replication

Background/Aims: The aim of this study is to clarify the differences of host immune responses between acute self-limited and chronic persistent hepatitis B virus (HBV) infections by quantitative and qualitative analysis of HLA-A*2402-restricted HBV-specific CD8+ T cells. Methods: HBV-specific CD8+ T cells in peripheral blood mononuclear cells (PBMCs) from patients infected with HBV were analyzed by flow cytometry using two HLA-A*2402–HBV peptide tetrameric complexes. Results: High numbers of HBV-specific CD8+ T cells were detected in acute phase PBMCs from most individuals with acute HBV infection while the number of these cells was greatly reduced in recovery phase PBMCs. HBV-specific CD8+ T cells were not detected in PBMCs from individuals with chronic HBV infection except for one patient during acute exacerbation. HBV-specific CD8+ T cells were induced by in vitro peptide stimulation in PBMCs from chronic HBV carriers with a low level of serum HBV-DNA but not from those with a high level of serum HBV-DNA. CD28CD45RA phenotype analysis showed that HBV-specific CD8+ T cells in acute phase PBMCs predominantly express a memory T cell phenotype. Conclusions: HBV-specific memory CD8+ T cells may play a crucial role in complete clearance of HBV from patients with acute HBV hepatitis.