Human interferon and cell growth inhibition. VII. Reversibility of interferon activities

Interferon (IFN) components isolated from human leukocyte-derived alpha IFN preparations were tested for reversibility of activities in four different human cell lines. As expected, antiviral activity was not reversed by removal of the IFN-containing medium. Growth inhibition by the anticellular component was completely reversible by washing of the cultures, while that of the antiviral component could not be reversed even after careful washing. The results with the components are in agreement with the findings with IFN in the different cell lines. The present study support earlier suggestions that at least two mechanisms of action are involved in growth regulation by IFN in various cell lines.