OBJECTIVETo study the dynamic changes of B7-H1 expression on myeloid dendritic cells (mDCs) and T cells in chronic hepatitis B (CHB) patients undergoing PEG-IFN alpha-2a therapy, and to analyze the association of the changes with the efficiency of interferon-alpha therapy.

METHODSExpressions of B7-H1 on mDCs and T cells in 14 patients with chronic HBV infection, including 6 responders and 8 non-responders to the antiviral therapy, were monitored by using flow cytometric analysis. Peripheral blood mononuclear cells from patients were incubated in vitro and the numbers of IFN-gamma-producing antigen-specific T cells were measured using ELISPOT assay.

RESULTSB7-H1 expressions by mDCs, CD4+ T cells and CD8+ T cells were all significantly upregulated at 4 weeks after starting PEG-IFN alpha-2a therapy. After this time point, B7-H1 expressions persistently decreased in the responders to the antiviral treatment, while non-responders maintained high levels of B7-H1 expression. In addition, the frequency of HBV-specific IFN-gamma-producing T cells significantly increased in the responders, but significantly decreased in the non-responders. Blocking the B7-H1 signal pathway increased the numbers of HBV-specific IFN-gamma-producing T cells in both the responders and non-responders.

CONCLUSIONDynamic changes of B7-H1 expression by mDCs and T cells in CHB patients undergoing PEG-IFN alpha-2a therapy can predict the efficiency of the therapy. Blocking the B7-H1 inhibitory pathway likely enhances the antiviral cellular T-cell responses.