Sterically stabilized cationic liposomes improve the uptake and immunostimulatory activity of CpG oligonucleotides

Immunostimulatory CpG oligonucleotides (ODN) show promise as immune adjuvan ts, anti-allergens, and immunoprotective agents. Increasing the bioavailabi lity and duration of action of CpG ODN should improve their therapeutic uti lity. Encapsulating ODN in sterically stabilized cationic liposomes provide s protection from serum nucleases while facilitating uptake by B cells, den dritic cells, and macrophages. In a pathogen challenge model, sterically st abilized cationic liposomes encapsulation doubled the duration of CpG ODN-i nduced immune protection. In an immunization model, coencapsulation of CpG ODN with protein Ag (OVA) magnified the resultant Ag-specific IFN-gamma and IgG responses by 15- to 40-fold compared with Ag plus CpG ODN alone. These findings support the use of sterically stabilized cationic liposomes to si gnificantly enhance the therapeutic efficacy of CpG ODN.