Immunospecific targeting of liposomes to erythrocytes.

Immunoliposomes were made by covalently linking Fab' fragments (from rabbit antimouse erythrocyte IgG) to reverse-phase evaporation vesicles (REV) via maleimido-4-(p-phenylbutyrate) phosphatidylethanolamine (MPB-PE) as anchor molecule. These immunoliposomes were characterized in terms of size, charge, stability and antigen binding capacity. The effect of the liposomal Fab' density on the interaction with the target cell was studied. Two isolation methods were tested to separate free Fab' from liposomally bound Fab'. The necessity of deactivation of remaining reactive sites with dithiothreitol preincubation to increase the specificity of immunoliposome target cell interactions was demonstrated.