Mast cell- and dendritic cell-derived exosomes display a specific lipid composition and an unusual membrane organization

Biochem J. 2004 May 15;380(Pt 1):161-71. doi: 10.1042/BJ20031594.


Exosomes are small vesicles secreted from multivesicular bodies, which are able to stimulate the immune system leading to tumour cell eradication. We have analysed lipids of exosomes secreted either upon stimulation from rat mast cells (RBL-2H3 cells), or constitutively from human dendritic cells. As compared with parent cells, exosomes displayed an enrichment in sphingomyelin, but not in cholesterol. Phosphatidylcholine content was decreased, but an enrichment was noted in disaturated molecular species as in phosphatidylethanolamines. Lyso(bis)phosphatidic acid was not enriched in exosomes as compared with cells. Fluorescence anisotropy demonstrated an increase in exosome-membrane rigidity from pH 5 to 7, suggesting their membrane reorganization between the acidic multivesicular body compartment and the neutral outer cell medium. NMR analysis established a bilayer organization of exosome membrane, and ESR studies using 16-doxyl stearic acid demonstrated a higher flip-flop of lipids between the two leaflets as compared with plasma membrane. In addition, the exosome membrane exhibited no asymmetrical distribution of phosphatidylethanolamines. Therefore exosome membrane displays a similar content of the major phospholipids and cholesterol, and is organized as a lipid bilayer with a random distribution of phosphatidylethanolamines. In addition, we observed tight lipid packing at neutral pH and a rapid flip-flop between the two leaflets of exosome membranes. These parameters could be used as a hallmark of exosomes.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cell Line
  • Cholesterol / analysis
  • Chromatography, Thin Layer
  • Dendritic Cells / chemistry*
  • Dendritic Cells / physiology
  • Electron Spin Resonance Spectroscopy
  • Endosomes / chemistry
  • Endosomes / ultrastructure
  • Exocytosis*
  • Fluorescence Polarization
  • Humans
  • Hydrogen-Ion Concentration
  • Lipid Bilayers
  • Lysophospholipids / analysis
  • Mast Cells / chemistry*
  • Mast Cells / physiology
  • Membrane Fluidity
  • Membrane Lipids / analysis*
  • Monoglycerides
  • Nuclear Magnetic Resonance, Biomolecular
  • Phosphatidylethanolamines / analysis
  • Phospholipids / analysis*
  • Rats
  • Sphingomyelins / analysis


  • Lipid Bilayers
  • Lysophospholipids
  • Membrane Lipids
  • Monoglycerides
  • Phosphatidylethanolamines
  • Phospholipids
  • Sphingomyelins
  • bis(monoacylglyceryl)phosphate
  • Cholesterol