Immunomodulatory effects in vitro of F protein of hepatitis C virus

Abstract

Objective To investigate the immunomodulatory effects of F protein of hepatitis C virus to dentritic cells (DC) and T cells. Methods Fgene of hepatitis C virus was cloned and F protein was expressed and purified. A total of 42 patients with chronic hepatitis C (CHC) and 30 healthy controls were enrolled in this study to detect the positive rate of serum anti-F protein. We separated the peripheral blood mononuclear cells (PBMC) , and induced to differentiate DC cells in vitro. DC was stimulated by F protein and the expression level of CD69, CD80, CD95, CD95L were detected by flow cytometry. The PBMC were stimulated by purified F protein and the cytokines like IFNγ, IL-12, IL-4, IL-10 in the culture supernatant were detected by ELISA. Results High purity (0.8 mg/mL, purity>90%) of F protein was produced in this study. The prevalence of anti-F protein in these 42 CHC patients was 42.88% (18/42) . CD69, CD80, CD95, CD95L on DC was significantly up-regulated after stimulation by F protein, and the expression level of these markers were all higher in CHC patients comparing with healthy controls (t=2.824, 3.707, 4.788, 3.550 respectively, all P<0.05) . Th1 cytokines like IFN-γ and IL-12 produced by PBMC in CHC patients after stimulation were much lower than healthy controls (t=4.583, 3.708 respectively, all P<0.05) , but Th2 cytokines IL-4 and IL-10 were much higher than healthy controls (t=3.483, 2.872 respectively, all P<0.05) . Conclusions HCV F protein is able to induce production of specific anti-F antibodies, up-regulate the expression of makers of activation and apoptosis, and promote the imbalance of Th1/Th2 cytokines. Key words: Hepacivirus; F protein; Dentritic cells; T lymphocytes