Description_x000D_ Application_x000D_ Lipid A molecules compose the lipid membrane anchoring core components of endotoxins produced by Gram-negative bacteria. Lipid A molecules induce immune responses. Structually, lipid A molecules are composed of two glucosamine unites with varied, species dependent, fatty acyl chain number and identity and degree of phosphorylation._x000D_ Lipid A, diphosphoryl from Salmonella entericaserotype Minnesota Re 595 may be used in comparative assessment of the antigenicity of specific structures within different LPA molecules and analogues.