RED-BLOOD-CELL LIPIDS FORM IMMISCIBLE LIQUIDS

Monolayers at the air-water interface were prepared from lipids extrac ted from human red blood cells. Epifluorescence microscopy was used to show that monolayers simulating the inner and outer leaflets of the r ed cell membrane form immiscible liquid phases with critical points at surface pressures of 21 and 29 dyn/cm. At these pressures the monolay er lipid density is comparable to that in the red cell membrane. This suggests that lipid bilayers of a red blood cell are near a miscibilit y critical point, which should significantly affect the biophysical pr operties of the red cell membrane. [S0031-9007(98)07922-8].