Immune characteristics of different immune phases in natural course of chronic HBV infection.

Background/aims The hepatitis B virus (HBV) infection course is divided into 4 immune phases which were mainly characterized by clinical markers. We investigated the immune markers, especially inhibitory receptors, cytokine and chemokine expressions among the immune phases especially between immune tolerance (IT) phase and immune control (IC) phase. Methodology Blood and serum samples of 64 patients and serum samples of 22 healthy controls were obtained. We used flow cytometric methods for measurements of PD-1, PD-L1 and flow fluorescence immunoassay for the serum cytokines and chemokines concentrations. IL-27 was measured by ELISA and the receptor IL-27R was detected too. Results The proportions of PD1 positive cells in CD4+, CD4+CD45RO+, and CD8+ T-cell subsets in IC phase were greater than in IC phase. The frequencies of PD1 expressions in CD8+pentamer+ and CD8+CD45RA-pentamer+ T cells were higher in IC phase than in IT and ICC phases. The serum concentration of IL-27 in IT group was higher than in IC, ICC and HC groups. Concentrations of cytokines TNF-α and IL-10 and chemokines RANTES, IL-8 and IP-10 were higher in HBV infected patients. Conclusions The reduction of percentages of PD-1 positive cells may contribute to estimate entering the IC phase and decide the opportune moment to start antivirus therapy.