Immunostimulatory Nanoparticle Adjuvants

Non-liposome, non-micelle particles formed of a lipid, an additional adjuvant such as a TLR4 agonist, a sterol, and a saponin are provided. The particles are porous, cage-like nanoparticles, also referred to as nanocages, and are typically between about 30 nm and about 60 nm. In some embodiments, the nanocages include or are administered in combination with an antigen. The particles can increase immune responses and are particularly useful as adjuvants in vaccine applications and related methods of treatment. Preferred lipids, additional adjuvants including TLR4 agonists, sterols, and saponins, methods of making the nanocages, and method of using them are also provided.