ABSTRACT
Liposome-Bound and Free Protein ....................................... 32 E. Measurement of Liposome-Cell Binding ................................. 34 F. Measurement of the Delivery of Liposomal Contents into Cell In Vitro .. 34 G. Circulation of Antibody-Bearing Liposomes In Vivo ..................... 38
The major orientation of our laboratory is that of the biology of cells of immunologic interest. In these studies, liposomes have been of considerable value, because they have permitted construction of a number of model systems for ligand-cell interaction. These include evaluation of the binding of hapten-bearing liposomes to cells expressing receptors for the hapten and studies on the opsonization of the hapten by antibody to evaluate immunoglobulin Fe receptor-mediated binding and endocytosis. 1-3
Limitations of this approach are apparent if the aim is to construct liposomes whose repertoire of potential binding sites is large. The most versatile ligand of which one can conceive is antibody; fortunately as a result of hybridoma technology, it is now possible to obtain monoclonal antibodies to dozens of cell-surface proteins. We investigated whether the coupling of monoclonal antibody to liposomes would preserve the specificity of the antibody on the liposomes, and whether the antibody-mediated binding of liposomes to cells would result in the delivery of the contents of the liposomes into the cells.
