CATIONIC LIPOSOME-MEDIATED EFFICIENT INDUCTION OF TYPE-I INTERFERONS BY A LOW-DOSE OF POLY I-POLY C IN MOUSE-CELL LINES

Double-stranded polyriboinosinic acid:polyribocytidylic acid (poly I:p oly C) is a powerful inducer of type I interferons (IFNs). However, th e dose of poly I:poly C required for efficient IFN induction is so hig h as occasionally to be cytotoxic, In this work, we examined the IFN-i nducibility of poly I:poly C complexed with several cationic reagents in mouse fibroblast L cells and found that Lipofectin and LipofectACE can induce the production of a substantial amount of type I IFNs (most ly beta-type) even at a two-order lower dose compared with poly I:poly C alone. Such effects of poly I:poly C were optimal at 0.1 mu g/ml fo r 2-10 mu g/ml of Lipofectin and LipofectACE. These conditions caused no significant cytotoxicity in the recipient cells, Furthermore, a sho rt treatment (less than 10 min) with the complexes was sufficient for the maximum induction. This IFN induction method was applicable to oth er cell types and other species including human. Hence, our observatio ns may pave the way for clinical application of the IFN inducer.