Biochemical, Morphological, and Ultrastructural Studies on the Uptake of Liposomes by Murine Macrophages

Avraham Raz, Corazon Bucana, William E. Fogler, George Poste, Isaiah J. Fidler

Research output: Contribution to journalArticle

112 Scopus citations

Abstract

The interaction of multilamellar liposomes with mouse peritoneal macrophages cultured in vitro has been examined. The principal mechanism of liposome uptake by these cells is by phagocytic engulfment. Studies with radiolabeled liposomes demonstrated that they are incorporated into macrophages as intact structures and that treatment of macrophages with inhibitors of phagocytosis prevents liposome uptake. Incubation of macrophages with liposomes containing encapsulated fluores-cein-labeled bovine serum albumin resulted in localization of fluorescence within discrete cytoplasmic vacuoles. Ultrastructural observations confirmed that liposomes were internalized and were enclosed within phagosomes. Electron microscopy also revealed that, by 24 hr following phagocytosis, adjacent phagosomes containing liposomes prepared from bovine brain phosphatidylserine, egg phosphatidylcholine, and lysolecithin (mol ratio, 4.95/4.95/0.1) fused within the cytoplasm. In contrast, phagosomes containing neutral liposomes consisting solely of egg phosphatidylcholine did not fuse and remained as discrete single structures. Negatively charged bovine brain phosphatidylserine/egg phosphatidylcholine/lysolecithin liposomes were phagocytosed at a much faster rate (12 times faster) than were neutral egg phosphatidylcholine liposomes.

Original languageEnglish (US)
Pages (from-to)487-494
Number of pages8
JournalCancer Research
Volume41
Issue number2
StatePublished - Feb 1 1981
Externally publishedYes

ASJC Scopus subject areas

  • Oncology
  • Cancer Research

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