Endotoxin adsorbents in extracorporeal blood purification: do they fulfill expectations?

Lipopolysaccharides (LPS) are extremely strong stimulators of inflammatory reactions, act at very low concentrations, and are involved in the pathogenesis of sepsis and septic shock. Because of its toxicity, the efficient removal of endotoxin from patients' blood is very important in clinical medicine. The purpose of this study was to determine the endotoxin adsorption capacities of commercial endotoxin adsorbers for endotoxin removal in buffer solution, protein solution, serum and heparinized plasma; some of these were also characterized in whole blood. The tested LPS adsorbers were Toraymyxin® PMX-20R, Alteco® LPS Adsorber, DEAE-Sepharose, Polymyxin B-Agarose, and EndoTrap® red.

The adsorber materials were tested in buffer and protein solutions spiked with fluorescently labeled LPS (100 ng/ml). Additionally, batch tests with LPS-spiked serum, heparinized plasma and whole blood were performed with an LPS concentration of 5 ng/ml. Additionally, the washing solutions of the two tested Polymyxin B (PMB)-based adsorbers were analyzed for PMB release to determine if the resulting LPS inactivation was caused by PMB leakage.

The results show that DEAE-Sepharose was most effective in LPS adsorption. Of the other tested endotoxin removal materials, only the PMB-based adsorbers were able to reduce the LPS activity. However, we were able to show that the reduction in LPS activity was caused by desorbed PMB, which inactivates endotoxins.

None of the adsorbents that were tested in this study showed promising results for potential use in extracorporeal blood purification.