The requirement of lipids for the formation of immunostimulating complexes (iscoms)

The iscom--immunostimulating complex--is a highly immunogenic formulation of microbial membrane antigens. The biochemically analyzed components of the iscom are the protein and the glycoside Quil A. Continued analysis of the iscom showed that the protein moiety--the antigen--does not contribute to the iscom as a construct. Instead, cholesterol and Quil A are the essential structural components assembled together into a typical cage-like structure. A more "fluid" lipid, such as phosphatidylcholine, is needed to facilitate the incorporation of amphipathic poly- or oligopeptides into the iscom matrix.