HVJ (Sendai Virus) Stimulates Release of Interferon from Leukocytes Used Once for Interferon Production By KAYOKO MATSUMOTO, * YASUKO NAKAMURA,

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 howed 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. Interferon (IFN)-ct derived from leukocytes of healthy volunteers i produced at the Osaka Blood Center using the method of Mogensen & Cantell (1977). Despite the advantages of this system, leukocytes are only available in limited quantity. Therefore, we investigated the possibility of re-use of the leukocytes for IFN production, and found that a second yield of about 30000 International Units (IU)/ml of IFN could be obtained