Removal of gram-negative endotoxin from solutions by affinity chromatography.

Endotoxins liberated by gram-negative bacteria are frequent contaminants of aqueous and physiological solutions. Because of their potent biological effects in vivo and in vitro, it is often necessary to eliminate even minute quantities of endotoxin from such solutions. A process is described which exploits the high binding affinity of polymyxin B for the lipid A moiety of most endotoxins in order to remove endotoxins from solutions by chromatography on polymyxin B Sepharose 4B. This method was simple, very effective, resulting in essentially complete removal of several endotoxins from heavily contaminated solutions (1-10 micrograms/ml by Limulus amoebocyte lysate assay) and employed mild physiological conditions.