Enhancement of Cell Mediated Immunity Through Non-Specific Immunostimulation with Liposome Encapsulated Gamma-Interferon

Abstract : The ability of liposome-encapsulated gamma interferon (LIP-gamma IFN) to stimulate mouse cell-mediated immunity was assessed both in vivo and in vitro. The enhancement of the cell-mediated immune response was demonstrated in vitro by a chemiluminescent assay which measured the phagocytic activity of peritoneal macrophages. Peritoneal macrophages harvested from mice treated with gamma interferon (gamma IFN) or muramyldipeptide showed significant increases in both macrophage yield as well as in ability to phagocytize zymosan particles. However, when treated with gamma IFN encapsulated within liposomes both macrophage yield and phagocytic activity further increased by at least 100% over unencapsulated gamma IFN. Using the in vivo influenza mouse protection model, intranasally administered LIP-gamma IFN resulted in a 70% survival rate to mice challenged intranasally with 10 LD50 doses of influenza A/PR/8 virus compared with a 20% survival rate with free gamma IFN. Together these result suggest that liposome encapsulation increases gamma IFN efficacy in providing non-specific stimulation of the cell-mediated immune system.