RESUMO
The reverse phase evaporation method was used to prepare lipid bilayer membrane vesicles containing 212Pb and other markers of high specific activity. Electron microscopy and microfiltration were used to measure the sizes of the liposomes. Isotopes were released from the liposomes during exposure to serum and this leakage was prevented by complexing of small molecules with proteins or by precipitating particulate complexes within the liposomes. The in vivo distribution of 212Pb liposomes differed from the distribution of free 212Pb in that the reticuloendothelial system cleared the liposomes. Liposomes with surface dinitrophenol hapten were highly immunogenic and the humoral response to dinitrophenol was nonspecifically suppressed by 212Pb liposomes.
