[Distribution of solid liposomes on the surface of an epithelial cell layer]

A study was made of the adhesion of liposomes, composed of dipalmitoyl- or di-stearoylphosphatidycholine, on the surface of epithelial cells in culture. Sodium fluorescein was entrapped in liposomes for their visualization by fluorescence microscopy. It is found that sonicated unilamellar liposomes adhere predominantly along the sheet margins. Multilamellar liposomes and lipid-coated carmine particles adhere over the whole cellular surface. However, their adhesion along sheet margins was stronger, as evidenced by a brief trypsin treatment. A prolonged trypsin treatment removed all types of liposomes from the cell surface. After the cells were partly detached from each other, small liposomes readily adhered to the newly accessible cell margins. The existence of special lipid membrane-binding proteins on the cell surface is suggested.