Expression of co-stimulatory molecules B7-2 and PD-L1 on peripheral blood mononuclear cells in patients with chronic hepatitis B virus infection

Abstract

Objective To explore the roles of the expression of the co-stimulatory molecule, B7-2, and the co-inhibitory molecule, PD-L1, on peripheral blood mononuclear cells in the mechanism of immunotolerance in chronic hepatitis B virus infection. Methods Thirty HBV infected patients in the immunoreactive phase and 20 patients in the immunotolerant phase were enrolled in the study, while 20 healthy volunteers were used as controls. RT- PCR and real-time PCR methods were used to detect the expression levels of B7-2 and PD-L1 mRNA in peripheral blood mononuclear cells in chronic HBV infected patients. Results The B7-2 expression in immunoreactive and immunotolerant patients was significantly lower than that in the controls ( P all < 0.01); B7-2 expression in immunoreactive patients was significantly lower than in immunotolerant patients ( P < 0.01). PD-L1 expression in immunoreactive patients and immunotolerant patients was significantly higher than that in normal controls ( P all < 0.01). The PD-L1/B7-2 ratios in immunoreactive and immunotolerant patients were significantly higher than that of the healthy controls ( P all < 0.01); the PD-L1/B7-2 ratio was significantly higher in the immunoreactive patients than in the immunotolerant patients ( P < 0.01). Conclusion In chronic HBV infection, changes in the expression of co-stimulatory and co-inhibitory molecules imply a protective adjustment against the patient's immune response that may result in increased immunotolerance and persistent HBV infection.