Characteristics of Circulating T Cell Receptor γδ T Cells from Individuals Chronically Infected with Hepatitis B Virus (HBV): An Association between Vδ2 Subtype and Chronic HBV Infection

Background. To date, few studies have been conducted to determine whether T cell receptor (TCR) gamma delta T cells are involved in hepatitis B virus (HBV) infection. This study was performed to assess the quantity and immune function of TCR gamma delta T cells in the blood of patients with chronic HBV infection and to analyze the relationship between proportions of TCR gamma delta T cells and both proportions of other immune cells and clinical parameters. Methods. Flow cytometry was used to detect the proportions of TCR gamma delta T cells and other immune cells in the peripheral blood of 46 asymptomatic carriers (AsCs) of HBV, 95 patients with chronic hepatitis B (CHB), and 29 healthy donors (HDs). The immune functions of TCR gamma delta T cells from 5 AsCs, 6 patients with CHB, and 5 HDs were assessed by cytokine secretion and cytotoxity assays. Results. The difference in the proportion of the V(delta)2 T cell subtype between HDs and patients was significant. For the patients, the proportion of V(delta)2 T cells was negatively correlated with alanine aminotransferase, aspartate aminotransferase, and total bilirubin levels. The differences in interferon (IFN)-gamma secretion and cytotoxicity between patients and HDs were significant. Conclusions. The proportion of circulating V(delta)2 T cells was significantly decreased in patients with chronic HBV infection, and this was accompanied by a strong immune response in the liver. IFN-gamma secretion and TCR gamma delta T cell cytotoxicity was lower in patients than in HDs.