Targeting of macromolecular carriers and liposomes by antibodies to myosin heavy chain.

Macromolecular carriers and liposomes were covalently coupled to monoclonal antibodies against cardiac myosin heavy chain. Deferoxamine-modified polymers bound tightly with 67Ga and 68Ga radioisotopes. Ternary deferoxamine-polylysine antibody conjugates specifically targeted the radioisotopes to a myosin-coated microplate. Scatchard analysis revealed a high affinity of the conjugate for the target with a Kas of approximately 10(8) M-1. Liposomes that contained immobilized antimyosin antibodies were targeted specifically to the myosin-coated plate. Additional coating of these liposomes with polyethylene glycol reduced specific binding to the target in vitro. However, because of the presence of polyethylene glycol on the surface of liposomes, these liposomes had a long half-life and slowly cleared from the blood-stream after intravenous injection. These immunoliposomes showed up to 16- to 18-fold specific localization to the necrotic areas of the myocardium in rabbits with experimental infarction.