Liposomes as a carrier for mannophosphoinositide antigens of mycobacteria.

Phosphatidylcholine liposomes have been used as carriers of mannophosphoinositides (PIMs) of mycobacteria to examine their immunological properties. PIMs incorporated in egg phosphatidylcholine (EPC) liposomes elicited both humoral and cell-mediated immune responses in mice. Addition of cholesterol at 43 mole% to PC enhanced the immune responses while the reverse was observed with EPC liposomes bearing negative or positive charge. Liposomes made of dioleoylphosphatidylcholine (DOPC) with cholesterol (43 mole%) proved to be a better immunoadjuvant with this antigen as compared to those made of EPC or dipalmitoylphosphatidylcholine (DPPC). Our results suggest that DOPC liposomes containing cholesterol are better carriers for PIMs-antigen as compared to Freund's incomplete adjuvant.