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. (C) 2002 European Association for the Study of the Liver. Published by Elsevier Science B.V. All rights reserved.