Pyrogen retention by the Asahi APS-650 polysulfone dialyzer during in vitro dialysis with whole human donor blood

The purpose of this study was to test the pyrogen permeability of the new A sahi polysulfone APS 650 (APS) dialyzer membrane with a high permeability f or middle molecules (up to 40 kDa) in comparison with the high-flux Freseni us polysulfone F60S (F60S) membrane. Dialyzers were tested in parallel in v itro dialysis experiments with whole human donor blood in the blood compart ment and contaminated bicarbonate dialysate in the dialysate compartment. D ialysate was contaminated by a filtrate (0.45 pm) of a Pseudomonas aerogino sa culture in bicarbonate dialysate. The production of interleukin-1 beta ( IL-1 beta) and tumor necrosis factor alpha (TNF alpha) in whole blood sampl es taken from the in vitro dialysis system was used to detect the passage o f cytokine inducing bacterial substances derived from P. aeruginosa across the two high-flux polysulfone membranes. Compared with a sterile control pe riod at the beginning of each experiment (n = 5), the TNF alpha inducing ac tivity in the dialysate increased from (mean +/- SEM) 42 +/- 12 pg/ml to 1, 288 +/- 356 pg/ml with F60S dialyzers and from 37 +/- 10 pg/ml to 928 +/- 2 49 pg/ml with APS dialyzers 30 minutes after the dialysate was contaminated . The IL-1 beta inducing activity in the dialysate increased similarly. In the presence of this significant contamination in the dialysate, whole bloo d circulating in the blood compartments for 60 minutes was not stimulated t o produce increased amounts of TNF alpha or IL-1 beta with neither of the t wo tested membranes. We conclude that F60S and APS membranes are equal in t heir ability to prevent the passage of cytokine inducing bacterial substanc es from highly contaminated dialysate into the patients' blood during hemod ialysis.