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.