The present invention provides an effective method for the transfection of dendritic cells by non-viral methods. The present invention provides this benefit by incubating dendritic cells and a specified transfection agent. The transfection agent comprises a polynucleotide and microparticles, with the microparticles being comprised of biodegradable polymer and cationic detergent. The dendritic cells and transfection agent are incubated for a time sufficient to transfect the dendritic cells with the polynucleotide.