Clinical utility of 2',5'-oligoadenylate synthetase activity measurement: using whole blood as a highly sensitive method to detect the effects of IFN.

Research progress on the pleiotropic effects of interferons (IFN) has thus far required detecting responses by weak IFN signals. The activity of 2',5'-oligoadenylate synthetase (2-5OAS) is a valuable indicator in the prognosis and IFN treatment of patients with viral diseases such as hepatitis B and C. Although serum samples generally are used to measure enzyme activity, their values depend on the exact conditions under which blood is stored and the degree of haemolysis that occurs during blood drawing or serum separation. This study presents an improved method of evaluating 2-5OAS activity by using whole blood samples containing heparin, which are frozen and then thawed, instead of serum samples. This method is more reliable, convenient, and 50-100 times more sensitive than the conventional methods of measuring serum 2-5OAS activity. The reliability and sensitivity of this improved method enables detection of the effects of low doses of oral IFN administration or changes in the IFN and cytokine system by infection or autoimmune diseases.