Immune Interferon Activates Cells More Slowly Than Does Virus-Induced Interferon 1

Summary

The kinetics of activation of the antiviral state by virus induced interferon and by mitogen-induced immune interferon have been studied comparatively. It has been found that both human and murine virus-induced interferons are able to activate the antiviral state after a brief (minutes) contact with the cells. In contrast, several hours were required for both human and mouse immune interferons to induce a comparable level of antiviral resistance. Experiments measuring the binding of the two interferons to cells showed that there was no significant difference in the rate and degree of binding, suggesting that a different total association of interferon with cells could not account for the slower kinetics of activation by immune interferon. Additionally, the possibility that some contaminants present in the immune interferon preparation could nonspecifically interfere with the rapid induction phenomenon is not supported by the finding that the rapid kinetics of cell activation by virus-induced interferon was not modified by the presence of immune interferon. The interesting possibility which remains is that the two interferons may activate cells by different mechanisms.

The authors are greatly indebted to Dr. G. Georgiades and Mr. M. Langford for the generous gifts of immune interferon and to Dr. S. Baron for helpful suggestions and criticism.