INVOLVEMENT OF SPECIFIC MECHANISM IN PLASMID DNA UPTAKE BY MOUSE PERITONEAL-MACROPHAGES

The binding and uptake of plasmid DNA encoding luciferase reporter gen e (pCMV-Luc) were studied in vitro using cultured mouse peritoneal mac rophages. A significant and time-dependent cellular association of [P- 32]pCMV-Luc with resident macrophages was observed at 37 degrees C and this decreased at 4 degrees C. The binding at 4 degrees C was saturab le and a Scatchard plot gave a maximum binding capacity of 0.81 mu g/m g-protein and a dissociation constant of 0.30 mu g/ml. The binding of [P-32]-pCMV-Luc was inhibited by polyinosinic acid, dextran sulfate an d salmon sperm DNA, but not by polycytidylic acid, dextran and EDTA A confocal microscopic study demonstrated that fluorescein-labeled pCMV- Luc was internalized at 37 degrees C while only cell surface binding o ccurred at 4 degrees C. No Significant luciferase gene expression was obtained after incubation with a high concentration (100 mu g/ml) of p CMV-Luc. These data suggest that plasmid DNA is taken up by macrophage s via a mechanism mediated by a receptor like the macrophage scavenger receptor. (C) 1998 Academic Press.