Priming of interferon action.

Pretreatment of L cell cultures with low levels of mouse interferon caused a more rapid development of and a greater degree of protection with subsequent exposure to higher levels of mouse interferon than that observed for control cultures. Such priming was a specific event which required cellular RNA synthesis. Priming by mouse fibroblast interferon, mouse immune interferon, and human leukocyte interferon was directly related to the plaque reduction titer of each of the interferons on L cells.