Unwanted Interactions of Maleimidophenylbutyrate-Phosphatidylethanolamine Containing (Immuno) Liposomes with CellsIn Vitro

The interaction between (immuno)liposomes and different (target and nontarget) cells was investigated in vitro. Maleimidophenylbutyrate-phosphatidylethanolamine (MPB-PE)-containing reverse-phase evaporation vesicles (REV-MPB-PE) were used; Fab' (polyclonal) fragments against mouse red blood cells (RBC) were selected as the homing device. Unwanted, nonspecific interactions were observed. these could be overcome by blocking the free reactive maleimide group of MPB-PE after Fab' coupling with dithiothreitol (DTT), or by storing the immunoliposomes for a period of 1 week before use. the specific interaction between immunoliposomes and target cells was maintained during storage. Storage of MPB-PE liposomes before Fab' coupling to REV-MBP-PE, however, reduced the coupling capacity considerably.