[PD-1 expression in peripheral T cells of patients with HBV infection and its significance]

To analyze the expression levels of PD-1 (program death factor-1) in peripheral T cells from patients infected with HBV, and to investigate its relationship with HBV serological markers.

A total of 65 HLA-A2+ subjects, including 31 patients with chronic hepatitis B (CHB), 9 with acute resolved hepatitis B (AHB), 15 with HBV related liver cirrhosis (LC) and 10 healthy blood donators, were enrolled. The expression of PD-1 in peripheral T cells and PD-1 ligands PD-L1 and PD-L2 in PBMCs were determined by relative quantitative real-time PCR. The serum HBV markers, HBV DNA load and liver function were also measured.

Taken the PD-1 and PD-ligands expression in normal controls as a baseline level, the expression of PD-1 and PD-L1 from CHB patients was significantly increased, while the expression of PD-L2 was relatively low in all groups. In CHB patients, the PD-1 expression in peripheral T cells from patients with high viral load was much higher than that from those with low viral load or from normal controls. And the PD-1 expression level positively correlated with serum HBV DNA load (r=0.41, P<0.01) but not with serum ALT level.

Long-term exposure to HBV antigens in CHB patients may increase the expression of PD-1 in T cells and thus leads to the virus persistent infection.