(2'-5')oligo(A) synthetase as a monitor of interferon action in juvenile laryngeal papillomatosis.

Four children with juvenile laryngeal papillomatosis were treated with human leukocyte interferon (IFN-alpha) by intravenous infusions. In three cases the clinical course of the disease was effected favorably. Serum IFN titers and (2'-5')oligo(A) synthetase (OAS) levels in lymphocytes of the patients were measured once a week during therapy. Levels of serum IFN determined 15 min after the end of 1 h infusions corresponded to only 15%-40% of the amount infused. Comparable OAS activities in the four children were measured before infusion, i.e., one, two, or three days, respectively, after the preceding infusion, though mean IFN titers of the patients differed from each other (200-400 and 400-600 u/ml). This suggests a saturation of the lymphocytes' antiviral system by these IFN levels. A discontinuation for two weeks in the early phase of IFN treatment, accompanied by a decrease of the OAS activity in the lymphocytes to the basal level, resulted in a deterioration of the patient's condition. A change in treatment schedule causing a decrease of OAS activity to a lower, though still elevated level, for six weeks until the present did not influence the course of therapy. Therefore, we suppose that the maintenance of elevated levels of OAS activity in lymphocytes for some months may be a necessary, even though not always a sufficient, criterion for a successful therapy schedule in IFN treatment of juvenile laryngeal papillomatosis. In addition, our results suggest OAS activity to be suitable in monitoring effects of an IFN therapy.