Encapsulation of human fibroblast interferon activity in liposomes

The preparation is described of three types of liposomes containing biologically active human fibroblast interferon. Depending on the preparative method, up to 50% of the initial interferon activity could be recovered associated with the liposomes, 15-30% being entrapped into the aqueous space of the vesicles. Encapsulation into negatively charged liposomes is dependent on the acidic phospholipid content; liposomes bearing a net positive charge could capture more interferon than those with a negative charge but were toxic to the target cells. Expression of biological activity of liposomes encapsulated interferon was demonstrated by their antiviral activity and their ability to prime interferon induction.