Aim: To investigate if and how programmed death type-1 (PD-1) expression affects the natural course of hepatitis B virus (HBV) infection.
Methods: Sixty-four patients in different natural stages of chronic HBV infection were enrolled in this study. PD-1 expression in total T cells was detected by flow cytometry. Levels of total CD8+ T cell responses and proliferation in relation to PD-1 expression levels were analyzed with intracellular staining and PD-1/PD-L1 blockage.
Results: The PD-1 expression in T cells was dynamically changed during the natural course of chronic HBV infection, did not significantly increase in the immune tolerance phase, and returned to normal in the inactive virus carrier stage. Blockage of the PD-1/PD-L1 pathway could not affect the T-cell response in the immune tolerance and inactive virus carrier stages of chronic HBV infection. However, it could significantly restore the T-cell response in the immune clearance stage of chronic HBV infection. Furthermore, the PD-1 expression level in T cells was associated with the alanine aminotransferase level during the immune clearance stage of chronic HBV infection.
Conclusion: The PD-l/PD-L1 pathway plays a different role in T-cell response during the natural course of chronic HBV infection.