2',5'-Oligoadenylate synthetase activity as a responsive marker during interferon therapy for chronic hepatitis C.

The 2',5'-oligoadenylate (2-5A) synthetase is an intracellular enzyme induced by interferon (IFN). We evaluated the serum level of this enzyme in 25 patients affected by chronic hepatitis C and treated with recombinant IFN-alpha 2b. At the end of treatment, 14 patients were classified as responders and 11 as nonresponders. Before therapy initiation no significant differences in 2-5A synthetase levels among the patients were detected, while during therapy responders showed higher mean levels of 2-5A synthetase than nonresponders. An increase in the enzyme activity was observed after 1 month of therapy, and this trend was maintained in the following 2 months. The peak of 2-5A synthetase activity was found at the end of therapy. 2-5A synthetase levels were negatively correlated with serum alanine aminotransferase (ALT). This study suggests that 2-5A synthetase may be a useful marker to monitor IFN efficacy during treatment and to predict the clinical response.