HVJ (Sendai Virus) Stimulates Release of Interferon from Leukocytes Used Once for Interferon Production

Leukocytes, subjected once to interferon (IFN) induction by HVJ (Sendai virus), were studied for their capability to produce IFN after a second similar stimulus. Substantial amounts of IFN (about 30000 IU/ml) were recovered. Experiments using cycloheximide or actinomycin D and kinetic studies showed that this IFN originated mainly in IFN which resided within the cell as a result of the first induction and was released after the second stimulation. Increasing amounts of HVJ used for the second stimulus resulted in proportionally increased yields of IFN, reaching a plateau at the same dose of HVJ (1000 HAU/ml) as that which gave optimal yields after the first stimulation. Evidence is presented that the capacity of HVJ to trigger the production of a second IFN harvest is closely associated with its infectivity.