Compositions comprising the compound of formula are provided herein. Also provided are methods of enhancing an immune response of a subject to an antigen by administering the antigen and the composition. The enhanced immune response may be an humoral immune response, a CD4+ T cell response, a CD8+ T cell response or result in activation of antigen presenting cells. Methods of enhancing the immune response by intramuscular administration of an antigen and the composition including the compound of formula I are also provided.
