Increased Frequencies of Circulating IFN-γ-Producing Vδ1(+) and Vδ2(+) γδ T Cells in Patients with Asymptomatic Persistent Hepatitis B Virus Infection.

Hepatitis B virus (HBV) is a leading cause of liver cirrhosis and hepatocellular carcinoma. The outcome of HBV infection is largely determined by the host immune response, with virus-specific cytotoxic T cells being able to mediate immunity against HBV as well as causing liver pathology. γδ T cells are reported to be depleted in patients with HBV-associated liver disease. However, it is not known if these cells control HBV infection in patients with asymptomatic chronic HBV infection. In this study, the frequencies, phenotypes, and interferon-γ production were examined by circulating γδ T cell subsets in a group of asymptomatic HBV carriers with low viral loads and little evidence of liver disease. It is shown that γδ T cells expressing Vδ1 and Vδ2 T cell receptors and effector-memory phenotypes are found at higher frequencies in these patients compared to controls. Vδ2 T cells from the patients expressed interferon-γ significantly more frequently than Vδ2 T cells from healthy donors in the absence of ex vivo stimulation. These data suggest that effector-memory IFN-γ-producing Vδ2 T cells may contribute to the control of HBV in patients with asymptomatic infection, without mediating liver pathology.