Open AccessPhosphatidylserine as a determinant of reticuloendothelial recognition of liposome models of the erythrocyte surface.
Author(s) -
Theresa M. Allen,
Patrick Williamson,
Robert Schlegel
Publication year - 1988
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.85.21.8067
Subject(s) - phosphatidylserine , liposome , phospholipid , mononuclear phagocyte system , biophysics , biology , phagocytosis , membrane , biochemistry , microbiology and biotechnology , chemistry , immunology
Liposomes formulated to resemble the outer leaflet of the erythrocyte membrane were found to substantially avoid recognition and clearance by the reticuloendothelial system. When these models of the erythrocyte surface were modified by the incorporation of greater than 2 mol % of phosphatidylserine (PtdSer), their ability to remain in the circulation of mice was greatly reduced. To examine whether this altered behavior was the consequence of an alteration in bilayer organization induced by PtdSer, a method utilizing the fluorescent dye merocyanine 540 was used to assess the packing of external phospholipids. No significant difference in overall membrane lipid organization was detected between liposomes containing 2 or 3 mol % of PtdSer, at which dramatic differences in recognition and clearance occurred. These results exclude alterations in phospholipid packing as an indirect cause of increased clearance of PtdSer-containing liposomes and implicate PtdSer directly in recognition by the reticuloendothelial system.