A NEW ASSAY FOR BACTERIAL LIPOPOLYSACCHARIDES

The purpose of this study was to ascertain whether an assay for bacterial lipopolysaccharide (LPS) could be developed based on the specific, stoichiometric binding between Polymyxin B and lipopolysaccharides. Polymyxin B was covalently linked to Sepharose 4B and the LPS-binding capacity of the resulting gel determined by incubation with various amounts of radiolabeled LPS (14C-LPS) of known specific activity. Competitive binding studies showed an inverse linear relationship between the amount of unlabeled LPS added and the binding of14C-LPS. The assay enabled the detection of microgram quantities of LPS even though the specific activity of the14C-LPS used was very low. The study demonstrated the feasibility of a Polymyxin B-based assay for LPS, and possible ways in which the sensitivity of the assay may be increased are discussed. © 1990 Springer-Verlag New York Inc.