Lung capillary endothelial cell specific monoclonal antibodies target liposomes to mouse lung in vivo

A monoclonal antibody (MoAb), 273-34A, specifically binds to an antigen expressed almost exclusively in the lung. Within 15 minutes of injection, approximately 80 to 85% of the injected radioiodinated MoAb 273-34A accumulates in the lung. Approximately 90 to 95% of the recovered dose is constantly found in the lung for up to one week after tail vein injection. Ratios of MoAb 273-34A to a nonspecific control MoAb 135-14 are 250 to 285 times higher in the lung than the serum.

When this MoAb was coupled with palmitic acid and IOC incorporated into liposomes, the amount of ¹²⁵I-labelled liposomes recovered per gram of tissue was 12 times higher in the lung than in the liver at 15 minutes post injection, and 21.8 times greater at five hours post injection. At 24 hours post injection the amount of liposomes per gram of lung tissue was still 6.0 times the amount per gram of liver tissue. Liposomes conjugated to MoAb 273-34A locate in the lung 20 and 15 times greater than liposomes conjugated to control MoAb 135-14 at 15 minutes and 24 hours post injection, respectively.

The results indicate that this system can be used as a model for enhanced delivery of substances to the lung.