Immune clearance of liposomes inhibited by an anti-Fc receptor antibody in vivo.

In a study designed to evaluate the potential for in vivo manipulation of the circulation and tissue distribution of injected liposomes, mice were passively injected with antidinitrophenyl (anti-DNP) monoclonal antibodies of the IgG2a or IgG2b subclasses or were immunized with the nitrophenyl hapten bound to a protein carrier. They were then injected i.v. with 125I- and carboxyfluorescein-labeled, DNP-bearing liposomes. Circulation time of the DNP-bearing liposomes was markedly reduced in actively and passively immune mice, with increased deposition of liposomes in the liver. The increased clearance of liposomes could be abrogated by injection of a monoclonal antibody directed against the murine IgG Fc receptor (2.4G2). The results suggest that clearance of ligand-bearing reagent in the face of an immune response may be modified by specific immunologic manipulation in vivo.