[Interferon treatment for chronic hepatitis C]

To determine the factors influencing the response to interferon (IFN) therapy, we studied 156 patients with chronic hepatitis C who underwent IFN alpha treatment Either 9MU of recombinant IFN alpha 2a or 3MU of natural IFN alpha was administered daily for 2 weeks and then three times a week for 22 weeks. IFN responses were divided into three types on the basis of the results of the polymerase chain reaction (PCR) assay detecting the 5 noncoding regions of HCV in sera. A complete response (CR) was defined as sustained elimination of HCV for at least 6 months after treatment, partial response (PR) as HCV elimination for a limited period, no response (NR) as continuously HCV-RNA positive. HCV genotyping was done by PCR with genotype-specific primers, by analyzing the variations in nucleotide sequence within the core region of HCV, namely HCV-I, -II, -III and -IV. Quantitation of serum HCV-RNA was performed by competitive PCR assay using synthetic mutant RNA. CR was obtained in 43 patients, PR in 64, and NR in 49. The IFN responses, CR/PR/NR, were 7/10/3 in 20 patients with chronic persistent hepatitis histologically, 34/38/24 in 96 patients with chronic active hepatitis (CAH)2A, and 2/16/22 in 40 with CAH2B. Median values of pretreatment serum HCV-RNA amount (copies/ml) in CR, PR, and NR groups were 10(3.55), 10(4.56) and 10(5.97), respectively. On HCV genotyping of sera from 114 patients, HCV-I, -II, -III, -IV and mixed (II+of) were seen in 1, 94, 11, 6 and 2 patients, respectively. CR/PR/NR in patients infected with HCV-I, -II, -III, -IV and -II + IV were 0/0/1, 28/26/40, 3/5/3, 1/3/2 and 0/1/1, respectively. Patients who had low viremia levels were likely to show good IFN responses, and those who had progressed liver histologies were resistant to IFN therapy.