GENE-TRANSFER INTO RESPIRATORY EPITHELIAL-CELLS BY TARGETING THE POLYMERIC IMMUNOGLOBULIN RECEPTOR

A system for targeting foreign DNA to epithelial cells in vitro has be en developed by exploiting receptor-mediated endocytosis. The polymeri c immunoglobulin receptor transports dimeric immunoglobulin A and immu noglobulin M through epithelial cells, including those of the respirat ory tract, by binding the immunoglobulins at the basolateral surface a nd transporting them across the cell. Fab fragments of antibodies dire cted against the extracellular portion of the receptor, secretory comp onent, are similarly transported. Anti-human secretory component Fab f ragments were covalently linked to a polycation, and complexed to vari ous expression plasmids. When bound to an expression plasmid containin g the Escherichia coli lacZ gene ligated to the Rous sarcoma virus pro moter, the complexes transfected HT29.74 human colon carcinoma cells i nduced to express polymeric immunoglobulin receptor, but not those lac king the receptor. Primary cultures of human tracheal epithelial cells grown on collagen gels, which induce the expression of polymeric immu noglobulin receptor, were also transfected with the complexes. From 5 to 66% of the respiratory epithelial cells had beta-galactosidase acti vity after treatment, comparable to the percentage of cultured human t racheal epithelial cells that express polymeric immunoglobulin recepto r (8-35%). The addition of excess human secretory component (Fab ligan d) to the culture medium at the time of transfection blocked the deliv ery of DNA. The expression plasmid, either alone, complexed to the pol ycation, or complexed to a carrier based on an irrelevant Fab fragment , was not effective in transfecting either cell type. This DNA carrier system introduces DNA specifically into epithelial cells that contain pIgR in vitro.