INDUCTION OF INTERFERON-ALPHA BY INTERFERON-BETA, BUT NOT OF INTERFERON-BETA BY INTERFERON-ALPHA, IN THE MOUSE

The antigenicity of the interferon (IFN) produced in transgenic mice carrying an extra mouse IFN-β gene under the control of mouse metallothionein-I enhancer-promoter was examined after induction with Cd2+. Unexpectedly, IFN-α in addition to IFN-β was detected in the serum. Induction of IFN-α was also observed when recombinant mouse IFN-β was injected into normal mice. IFN-a was first detected in the circulation 6-10 hr after the administration of IFN-β, and after 12 hr, IFN-α became the major component of serum IFN. On the other hand, when IFN-a was injected, no production of IFN-β was observed. Messenger RNAs specific for IFN-α and endogenous IFN-β were detected in the spleen, though the amount of IFN-,B mRNA was much less than that of IFN-a mRNA. These mRNAs were not detected in other organs including the liver where exogenous IFN-β gene was markedly expressed. These observations showed that the expression of IFN-α is inducible by IFN-β in the mouse, and the spleen was suggested to be the main site of production. Possible mechanisms of the induction are discussed. © 1990.