Provided herein is an adjuvant formulation comprising a monophosphoryl lipid A (MPLA) containing liposome composition to saponin (e.g. QS 21) wherein the liposome composition comprises i) a lipid bilayer comprising phospholipids in which the hydrocarbon chains have a melting temperature in water of = 23°C and ii) cholesterol at a mole percent concentration of greater than about 50% (mol/mol) preferably about 55% to about 71% (mol/mol) or more preferably about 55% (mol/mol). The adjuvant formulation displays minimal toxicity of either lipid A or saponin.
