Preparation of asialofetuin-labeled liposomes with encapsulated human interferon-gamma and their uptake by isolated rat hepatocytes.

The selective delivery of human recombinant interferon (IFN)-gamma to isolated rat hepatocytes was studied with asialofetuin (AF)-labeled liposomes. AF-liposomes containing buffer solution were initially prepared by the detergent removal method, and IFN-gamma was subsequently encapsulated by the freeze-thawing method without loss of activity. Virtually no free [32P]IFN-gamma was internalized into isolated rat hepatocytes, whereas AF-liposomes containing [32P]IFN-gamma were taken up to a significant degree. Liposomal binding to the hepatocytes (estimated at 4 degrees C) was one-fifth of the uptake (estimated at 37 degrees C). Since the uptake was inhibited by the addition of free AF, AF-liposomes may be taken up by the action of galactose-binding protein on the hepatocytic cell surface. The liposome preparation method reported in this paper provides a useful means for the encapsulation of unstable macromolecules into AF-liposomes. AF-liposomes were found effectively to carry IFN-gamma into hepatocytes in vitro.