Lipid A and liposomes containing lipid A as antigens and adjuvants

Lipid A derived from Gram-negative bacterial. lipopolysaccharide is a potent adjuvant and antigen. Incorporation of lipid A into liposomes renders the liposomes themselves immunogenic, resulting in generation of specific antibodies that recognize either the individual liposomal lipids, or the unique pattern presented by the combination of lipids. Using liposomes containing lipid A, numerous polyclonal antisera and monoclonal antibodies have been produced against phospholipids, cholesterol, glycosphingolipids, and lipid A. Many of these antibodies have binding characteristics that are apparently similar to natural antibodies that are normally present in all human sera, and also antibodies that arise in response to various infections. Such antibodies probably represent a bridge between innate and adaptive immunity. The possibile utility of liposomes containing lipid A as a constituent of certain types of novel vaccines was suggested by the observation that murine monoclonal antibodies to liposomal. phosphatidytinositol-4-phosphate neutralized primary isotates of two different clades of HIV-1 in a human peripheral. blood mononuctear cell. neutralization assay. Published by Elsevier Ltd.