Protein-loaded chitosan nanoparticles modulate uptake and antigen presentation of hen egg-white lysozyme by murine peritoneal macrophages

Chitosan binds to negatively charged tripolyphosphate (TPP) by an electrostatic interaction driven by its positively charged amino group. This interaction allows developing stable nanoparticles suitable as a carrier and controlled release system for drugs and vaccines. We study the effect of chitosan nanoparticles (CNp) on the uptake and antigen presentation of the model protein hen-egg white lysozyme (HEL) to peritoneal macrophages isolated from mice. Results showed that after four hours of pre-incubation with a T-cell hybridoma line cocultured with murine peritoneal macrophages, only trace amounts of IL-2 were detected in treatments with HEL alone, whereas cocultures treated with HEL-CNp had already reached maximum IL-2 expression. Confocal microscopy studies showed that CNp had a higher uptake rate of the fluorescently labelled protein than the protein itself after 30 min of incubation with the peritoneal macrophages. Our results suggest that CNp system is a potential candidate for an oral vaccine delivery system.