Endotoxin binding by charged and uncharged resins

Cholestyramine (Dowex 1-X2), a strongly basic anion-exchange resin, has previously been shown to bind bacterial endotoxin, preventing both its toxicity and intestinal absorption. Because hemoperfusion through charged and uncharged resins is practical, a study was undertaken to test the endotoxin-binding characteristics of a number of resins. The resin to be tested was washed and swelled overnight, and 1 mg/ml of 51Cr-labeled endotoxin was added and the mixture, agitated and incubated at 37 degrees for a specific time period. In the Dowex 1 series, the 1-X2 was superior to the 1-X4 and 1-X8 in its ability to bind E. coli endotoxin, removing about 90% from solution in 15 min. Increasing mesh size seemed to offer more binding sites for each Dowex 1 resin. Activated charcoal adsorbed about 90% of the endotoxin also, but Amberlite XAD-2 showed little binding capacity. Injection of filtrate from unlabeled E. coli and S. typhosa resin-treated solution into rats, demonstrated that both Dowex 1-X2 and activated charcoal prevented the transaminase rise noted in animals injected with solutions not so treated. It is concluded that Dowex 1-X2 resin and activated charcoal efficiently remove endotoxin in vitro, and may offer a unique method for removing circulating endotoxin in vivo.