Background: A prospective study was conducted to evaluate the influence of host factors, including human leukocyte antigen (HLA), and viral factors, including hepatitis C virus (HCV) core antigen, on the response to interferon (IFN)-Alpha.
Methods: Natural IFN-Alpha was given to 66 patients with chronic hepatitis C at a dose of 9 million units per day for 2 weeks, followed by 9 million units three times a week for 22 weeks.
Results: Sustained virological response without detectable HCV RNA in serum 24 weeks after the end of IFN therapy was achieved in 21 patients, while it was not in 32 patients; the remaining 13 patients were not evaluated. HCV core antigen and HCV RNA started to decrease 1 and 4 weeks, respectively, after the commencement of IFN in responders ( P = 0.02 and P = 0.05, respectively). On univariate analysis, age of 50 years or less ( P < 0.001); lack of HLA DR6 ( P = 0.018) or DR52 ( P < 0.041); platelets more than 14 x 10(4)/mm(3) ( P = 0.031); HCV core antigen 500 fmol/l or less ( P = 0.001); and HCV RNA 100 KIU/ml or less were predictive of response. On multivariate analysis, age 50 years or less (odds ratio [OR], 4.009; P = 0.039); lack of HLA DR6 (OR, 8.130; P = 0.027); IFN-naive (OR, 11.63; P = 0.016); HCV core antigen 500 fmol/l or less (OR, 10.61; P = 0.007); and genotypes other than 1b (OR, 8.929; P = 0.010) were predictive of response.
Conclusions: Lack of HLA DR6 determined the response to IFN. HCV core antigen was useful in predicting and monitoring the response to IFN.