Interferon-α-induced CD100 on naïve CD8(+) T cells enhances antiviral responses to hepatitis C infection through CD72 signal transduction

OBJECTIVES: We investigated the effects of CD100 on naïve CD8(+) T cells during hepatitis C virus (HCV) infection after interferon-α (IFN-α) therapy to clarify the mechanism underlying the effect of IFN-α in enhancing the antiviral response. METHODS: The CD100 molecules on subsets of CD8(+) T cells were analysed with flow cytometry. The effects of CD100-overexpressing naïve CD8(+) T cells were determined with ELISAs and an MTT cytotoxicity assay. The role of CD100–CD72 signal transduction was analysed with a neutralization and transwell assays. RESULTS: HCV infection reduced CD100 expression on CD8(+) T cells, whereas IFN-α treatment significantly increased CD100 expression on naïve CD8(+) T cells. The increased CD100 interacted with the CD72 receptor and enhanced PBMC cytokine secretion (IFN-γ and tumour necrosis factor-α) and cytotoxicity. CONCLUSIONS: IFN-α-induced CD100 on naïve CD8(+) T cells promotes PBMC cytokine secretion and cytotoxicity through CD100–CD72 signalling during HCV infection.