Functional measurement of hepatitis C virus core-specific CD8+T-cell responses in the livers or peripheral blood of patients by using autologous peripheral blood mononuclear cells as targets or stimulators

As is widely recognized, CD8(+) cytotoxic T lymphocytes (CTLs) play a cruci al role in hepatitis C virus (HCV) infection, both in pathogenesis of liver injury and in clearing the virus. CTL studies with HCV-infected patients h ave been difficult because of the relatively low frequency of CTL precursor s in the peripheral blood and because the targeted epitopes vary depending on the human leukocyte antigen (HLA) types of the individuals. This study a ttempts to overcome these problems by assessing the feasibility of using au tologous peripheral blood mononuclear cells (PBMCs) expressing viral antige ns as stimulators or targets in order to monitor the CTL responses. Primary PBMCs were transduced using a retroviral vector pseudotyped with a vesicul ar stomatitis virus G glycoprotein expressing the HCV core gene. Additional ly, the vector-transduced PBMCs were used as targets of CTL assays to measu re the HCV core-specific CTL activities from the liver-infiltrating lymphoc ytes of six different HLA-type patients with chronic HCV infection. The cor e-expressing PBMCs also served as stimulators, allowing us to measure core- specific CD8+ T-cell responses by intracellular gamma interferon staining o f the peripheral blood of hepatitis C patients who had received treatment w ith alpha interferon plus ribavirin. This approach provides an efficient me ans of measuring antigen-specific CTL responses without HLA constraints.