Up-regulation of IL-18 by interferon alpha-2b/ribavirin combination therapy induces an anti-viral effect in patients with chronic hepatitis C.

Background/aims: Recent large prospective trials demonstrated that the combination therapy of interferon (IFN)-alpha/ribavirin significantly increased a sustained virological response rate in patients with chronic hepatitis C. However, the potential mechanism of ribavirin is not clear.

Methodology: Serum interleukin (IL)-18 and HCV-RNA titer were determined before and 2 weeks after administration in patients with chronic hepatitis C, who were treated with ribavirin in combination with IFN-alpha2b (combination group), and with IFN-alpha2b alone (monotherapy group).

Results: All HCV patients were genotype 1b. In the combination group, the decline of HCV-RNA level by treatment highly correlated with the IL-18 ratio (serum IL-18 level 2 weeks after administration/serum IL-18 level before administration). Similarly, the HCV-RNA level 2 weeks after administration inversely correlated with the IL-18 ratio. In contrast, the IL-18 ratio in the monotherapy group was lower. Furthermore, the decline of HCV-RNA level did not correlate with the IL-18 ratio in the monotherapy group.

Conclusions: This study suggests that ribavirin may contribute to the antiviral effect through up-regulation of IL-18 in combination with IFN in patients with chronic hepatitis C.