Influence of PD-1 on T cell immunity in the course of chronic HCV infection

Objective To explore the influence of PD-1 on peripheral T cells from chronic HCV patients during the process of T-cell-associated immune response.Methods Forty patients with chronic hepatitis C,10 patients with non-HCV liver disease,and 20 healthy controls were enrolled in our study.The expression of PD-1 on CD4+ and CD8+ T cells were detected by flow cytometry.ELISA was used for cytokine production of IFN-γ and IL-2 during allogeneic mixed leukocyte reactions(MLR).Results The percentage of PD-1+ distinct subpopulations of CD4+ T cells(38.61 ± 4.35) and CD8+ T cells(48.17 ± 5.16) were significantly increased in peripheral blood cells from patients with HCV compared with healthy individuals and patients with non-HCV liver disease(P 0.01).Furthermore,type 1-cytokine production of T cells was decreased.The blockage of PD-1 co-stimulatory signals could reverse the cytokine production.Conclusion Up-regulation of PD-1 on peripheral T cells from HCV patients may explain the reduction of T cell responsibility during the process of immunopathogenesis.