Fc receptor-mediated transcytosis of IgG-coated liposomes across epithelial barriers.

Drug carriers such as liposomes are not readily transported across cellular barriers that constitute epithelia. However, certain epithelia (rabbit yolk sac endoderm and enterocytes of suckling rat gut proximal small intestine) are well known to transcytose maternal IgG by Fc receptor-mediated endocytic events. We have shown that coating liposomes with appropriate IgG enhances their transport across these epithelia, as measured both by radioactivity indicative of liposomal membrane or entrapped 125I-PVP and [3H]inulin, and by the hypoglycemic effect of entrapped insulin. It is suggested that these transported liposomes follow a pathway of transcytosis in clathrin-coated vesicles, thus escaping lysosomal degradation.