title: Complement-dependent phagocytosis of liposomes.
abstract: In this article we describe an in vitro model for complement-dependent phagocytosis of liposomes. We have previously reported that complement-opsonized liposomes are avidly ingested by murine peritoneal or bone marrow-derived cultured macrophages. However, when the liposomes contained certain lipids, including phosphatidylinositol, ganglioside GM1, and sulfogalactosyl ceramide, that have been identified as causing prolonged circulation time in vivo, complement-dependent phagocytosis of the liposomes was greatly suppressed. We identify certain additional factors associated with suppressed complement-dependent phagocytosis, including, liposomal negative charge and liposomal prostaglandin E2 or thromboxane B2. Possible mechanisms responsible for suppression of complement dependent phagocytosis are suggested. We propose that suppression of complement-dependent phagocytosis could be a contributing factor in the promotion of increased circulation time of 'stealth' liposomes and that complement opsonization probably plays a role in vivo in removing liposomes from the circulation.
authors.affiliation: Department of Membrane Biochemistry, Walter Reed Army Institute of Research, Washington, DC 20307-5100.
authors.forename: N M
authors.initials: NM
authors.lastname: Wassef
authors.forename: C R
authors.initials: CR
authors.lastname: Alving
mesh_terms: D000818:Animals; D001853:Bone Marrow / Q000502:physiology; D002478:Cells, Cultured; D002784:Cholesterol / Q000494:pharmacology; D003165:Complement System Proteins / Q000378:metabolism*; D046508:Culture Techniques / Q000379:methods; D004134:Dimyristoylphosphatidylcholine / Q000378:metabolism*; D005732:Gangliosides / Q000378:metabolism; D006168:Guinea Pigs; D007075:Immunoglobulin M / Q000378:metabolism; D007700:Kinetics; D008051:Lipid Bilayers / Q000378:metabolism; D008081:Liposomes / Q000378:metabolism*; D017737:Macrophages, Peritoneal / Q000502:physiology*; D051379:Mice; D008809:Mice, Inbred C3H; D010587:Phagocytosis / Q000187:drug effects; D010743:Phospholipids / Q000494:pharmacology; D011458:Prostaglandins E / Q000378:metabolism; D013433:Sulfoglycosphingolipids / Q000378:metabolism; D013929:Thromboxane B2 / Q000378:metabolism; D013997:Time Factors
chemical_list: D005732:Gangliosides; D007075:Immunoglobulin M; D008051:Lipid Bilayers; D008081:Liposomes; D010743:Phospholipids; D011458:Prostaglandins E; D013433:Sulfoglycosphingolipids; D013929:Thromboxane B2; D003165:Complement System Proteins; D002784:Cholesterol; D004134:Dimyristoylphosphatidylcholine