Immune and non-immune responses to hepatitis C virus infection

Figure 1 Direct-acting antiviral therapy and immune function restoration in hepatitis C virus infection. In chronic hepatitis C infection, T cells having a narrow repertoire of TCRs mount a weak response to HCV antigens, and their effector functions are often impaired. Many CD8⁺ and CD4⁺ T cells express low levels of IFN-γ and IL-2 accompanied by up-regulation of PD-1 molecules in the liver. Development of T regulatory cells and compromised dendritic cell functions also contribute to T cell functional impairment. Recent data suggest that IFN-free direct-acting antivirals not only clear HCV in the majority of patients, but also result in the down-regulation of PD-1, leading to rapid restoration of virus-specific CD8⁺ T cell functions in patients[28]. HCV: Hepatitis C virus; IFN: Interferon; IL: Interleukin; PD-1: Program death-1; TCR: T cell receptor.