Use of immobilized histidine in assay for endotoxin in patients with liver disease.

The Limulus amebocyte lysate (LAL) test has the disadvantage of being influenced by various inhibitors and activators. We have developed a method for the LAL reaction that involves the specific adsorption and isolation of endotoxin using a membrane filter unit and immobilized histidine; in this present study we used the method to measure endotoxin in the plasma of patients with acute or chronic liver disease. The adsorbed endotoxins are separated from LAL-inhibitors or -activators by the membrane filter unit, and their activity is directly assayed with the LAL reagent in a filter cup without any inhibition or activation. The study population consisted of 23 subjects, 3 with fulminant hepatitis and 20 with cirrhosis (9 with esophageal varices and 11 without). All 3 (100%) of the samples of plasma from patients with fulminant hepatitis were positive for endotoxin, as were the samples of 7 (78%) of the 9 patients with cirrhosis and esophageal varices, and 2 (18%) of the 11 patients with cirrhosis but without such varices. The results suggested that this method appears to be useful for assaying the concentration of endotoxin in patients with fulminant hepatitis or cirrhosis of the liver.