Elevated levels of 2′,5′‐oligoadenylate synthetase activity in peripheral blood mononuclear cells and serum during acute exacerbation of chronic hepatitis B

We measured 2′,5′-oligoadenylate synthetase activity in peripheral blood mononuclear cells and serum of 14 HBsAg- and HBeAg-positive patients with chronic hepatitis B with or without acute exacerbation. Elevated levels of 2′,5′-oligoadenylate synthetase in peripheral blood mononuclear cells and serum were found in seven chronic hepatitis B patients with acute exacerbation, whereas in the remaining seven chronic hepatitis B patients without acute exacerbation, both levels were similar to those of normal subjects despite active hepatitis B virus multiplication. 2′,5′-Oligoadenylate synthetase levels in peripheral blood mononuclear cells and serum, which were not statistically different from those of normal subjects prior to acute exacerbation, increased during acute exacerbation from 3-to 23-fold over initial levels following elevations in ALT activity. 2′,5′-Oligoadenylate synthetase levels fluctuated over a normal range while ALT levels were elevated, and they returned to a baseline with ALT normalization. This suggests that the in vivo interferon system may be activated during acute exacerbation, and that this activation may not be a result of hepatitis B virus multiplication alone, but also of a host-immune response to hepatitis B virus multiplication. Three patients were treated with interferon during acute exacerbation. All three had elevated levels of 2′,5′-Oligoadenylate synthetase in peripheral blood mononuclear cells and serum just before treatment. 2′,5′-Oligoadenylate synthetase levels increased only 1.1 -to 2.2-fold over initial levels during treatment, with none of the patients clearing HBeAg during and after treatment. This suggests that interferon treatment may not be effective during acute exacerbation, since the in vivo interferon system has already been activated. Measurement of 2′,5′-oligoadenylate synthetase levels may be useful in evaluating the in vivo state of the interferon system and in determining the optimal timing of interferon treatment.