POTENCY OF ENDOTOXIN FROM BICARBONATE DIALYSATE COMPARED WITH ENDOTOXINS FROM ESCHERICHIA-COLI AND SHIGELLA-FLEXNERI

Endotoxin is a potent activator of the complement system and other hos t immunoregulators, including the cytokines, tumor necrosis factor alp ha, interleukin-1 beta, and interleukin-6. In this study, the potency of an endotoxin from bicarbonate dialysate was compared with endotoxin s from two enteric microorganisms, Shigella flexneri and Escherichia c oli. Endotoxin concentrations were standardized for the three endotoxi ns by use of the limulus amebocyte lysate turbidimetric assay. Endotox in potency was assessed by the comparative plasma concentrations of tu mor necrosis factor alpha, interleukin-1 beta, and interleukin-6 after an in vitro whole-blood challenge by each type of endotoxin. Blood co llected from 10 hemodialysis patients was spiked with 0.1, 1, and 10 n g/mL of E. coli and Shigella endotoxin and with 1 and 10 ng/mL of bica rbonate dialysate endotoxin. After incubation, plasma was separated an d frozen at -70 degrees C until assayed for cytokine concentrations. D ialysate endotoxin was found to be 10 to 100 times less potent than E. coli and Shigella endotoxins. It was concluded that there are signifi cant differences in the potency of endotoxins from different strains o f bacteria and that these differences should be noted when designing o r evaluating studies on the clinical effects of endotoxins in hemodial ysis settings.