Lipopolysaccharides (LPS), also known as lipoglyans and endotoxins, are large molecules consisting of a lipid and a polysaccharide composed of O-antigenm outer core and inner core joined by a covalent bond. They are found in the outer membrane of Gram-negative bacteria and elicit strong immune responses in normal mammalian cells. LPS from E. coli is particularly potent in systemic inflammation and have long been recongnized as a key factor in septic shock and also used in research to induce synthesis and secretion of growth promoting factors such as interleukins.

MD Biosciences provides lyophilized lipopolysaccharide (LPS) for in vivo and in vitro use. The LPS is isolated from Escherichia coli by a modification of the phenol extraction method of Westphal and Jann. This material has been extracted from bacterial cells walls of E. coli 055:B5. The endotoxin has been futher purified to remove traces of residual protein and nucleic acids, producing highly purified LPS. The LPS is essentially free of nucleic acid and protein and is chemically characterized with respect to their phosphate and KDO(2-keto-3-deoxyoctonate) contents. The highly purified LPS has been then re-extracted by the method of Manthey and Vogel to eliminate residual protein contamination.