title: Incorporation of recombinant gamma interferon into liposomes enhances its ability to induce peritoneal macrophage antitoxoplasma activity.
abstract: In this study we compared the ability of free- and liposome-incorporated murine recombinant gamma interferon (rIFN-gamma) to enhance peritoneal macrophage H2O2 release and antitoxoplasma activity in vitro. rIFN-gamma was efficiently (37 to 47%) incorporated into multilamellar vesicles composed of phosphatidylglycerol/cholesterol in a 2:1 molar ratio. The amount of rIFN-gamma incorporated into multilamellar vesicles and added to macrophages (0.1 to 1,000 U/ml) was quantitated with [3H]rIFN-gamma. The concentration of liposomal rIFN-gamma required to enhance macrophage H2O2 release (1 U/ml) and maximally inhibit Toxoplasma gondii growth (10 U/ml) was one-tenth the concentration required for free rIFN-gamma (10 and 100 U/ml, respectively). This increase in potency was observed in both thioglycolate-elicited and resident peritoneal macrophages. Control liposomes containing encapsulated buffer had no effect on the potency of free rIFN-gamma. The duration of macrophage activation induced by 24 h of liposomal rIFN-gamma treatment was also considerably longer than that induced by free rIFN-gamma (2 days versus less than 1 day). These data indicate that liposomal rIFN-gamma is more active than free rIFN-gamma as an inducer of macrophage microbicidal properties in vitro. This enhanced activity, combined with the potential for selective delivery of liposomal rIFN-gamma to phagocytic cells in vivo, may improve the therapeutic efficacy of rIFN-gamma in infections characterized by parasitization of phagocytes.
authors.affiliation: Department of Medicine, Yale University School of Medicine, West Haven, Connecticut 06516.
authors.forename: J W
authors.initials: JW
authors.lastname: Mellors
authors.forename: R J
authors.initials: RJ
authors.lastname: Debs
authors.forename: J L
authors.initials: JL
authors.lastname: Ryan
mesh_terms: D000818:Animals; D000981:Antiprotozoal Agents / Q000276:immunology / Q000494:pharmacology*; D005260:Female; D006861:Hydrogen Peroxide / Q000378:metabolism; D007371:Interferon-gamma / Q000276:immunology / Q000494:pharmacology*; D008081:Liposomes / Q000276:immunology; D008262:Macrophage Activation / Q000187:drug effects; D008264:Macrophages / Q000276:immunology* / Q000378:metabolism; D051379:Mice; D008807:Mice, Inbred BALB C; D010529:Peritoneal Cavity; D011994:Recombinant Proteins; D014122:Toxoplasma / Q000254:growth & development*
chemical_list: D000981:Antiprotozoal Agents; D008081:Liposomes; D011994:Recombinant Proteins; D007371:Interferon-gamma; D006861:Hydrogen Peroxide