title: Novel fluorescence method to visualize antibody-dependent hydrogen peroxide-associated "killing" of liposomes by phagocytes.
abstract: We have developed a new methodology to examine effector-cell-mediated immune attack using liposomes as targets. Hydrogen peroxide-associated killing of liposomes was observed with fluorescence intensification microscopy. Liposomes were composed of 98-99 mol % egg phosphatidylcholine and 1-2 mol % dinitrophenyl lipid hapten. Anti-dinitrophenyl IgG antibody was used to opsonize liposomes. Liposomes were loaded with dihydroxymandelic acid (DHMA) and peroxidase. Macrophage- or neutrophil-mediated recognition of liposomes triggers the release of H2O2 and other oxidative products. Upon interaction of H2O2 or OH radical with liposome contents, DHMA dimerizes forming a fluorescent derivative. Our studies indicate that individual living neutrophils and macrophages deposit oxidative products in a heterogenous fashion among bound targets.
mesh_terms: D000906:Antibodies; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D007111:Immunity, Cellular / Q000187:drug effects*; D008081:Liposomes; D008264:Macrophages / Q000276:immunology*; D008856:Microscopy, Fluorescence; D009504:Neutrophils / Q000276:immunology*; D010586:Phagocytes / Q000166:cytology / Q000276:immunology*; D010587:Phagocytosis / Q000187:drug effects*; D010713:Phosphatidylcholines
chemical_list: D000906:Antibodies; D008081:Liposomes; D010713:Phosphatidylcholines; D006861:Hydrogen Peroxide