Novel Insights into the Direct Removal of Endotoxin by Polymyxin B Hemoperfusion

AIM: To demonstrate the capacity of polymyxin B-direct hemoperfusion (PMX-DHP) column Toraymyxin® 20R (PMX-20R) in removing endotoxin (LPS) from perfused blood, serum and plasma. METHODS: Endotoxin-spiked bovine serum was perfused in PMX-20R as per the recommended performance testing protocol. Samples were taken at various time points to assess the amount of endotoxin removed during a 4-h session. In another set of experiments, FITC-labelled LPS (FITC-LPS) was spiked into a pool of human whole blood, followed by perfusion with the spiked blood for 2 h in order to allow FITC-LPS to bind PMX-20R. The amount of LPS was extracted from the columns and the amount of specifically bound LPS was determined by fluorometry. RESULTS: PMX-20R columns perfused with bovine serum had an average binding rate of 88%, equivalent to approximately 12 µg of LPS. When PMX-20R was perfused with human whole blood, the columns bound an average of 20 µg of FITC-LPS. CONCLUSION: PMX-20R can bind LPS in all the biological fluids tested. The calculated binding capacity of 12-20 µg LPS suggests that in septic cases where endotoxin is present in the circulation, PMX-20R is able to adsorb clinically significant levels of endotoxin.