NEW POLYETHER SULFONE DIALYZERS ATTENUATE PASSAGE OF CYTOKINE-INDUCING SUBSTANCES FROM PSEUDOMONAS-AERUGINOSA CONTAMINATED DIALYSATE

The use of bicarbonate dialysate and high-flux and reprocessed dialyze rs has raised concerns about the reverse transfer of dialysate contami nants into the blood compartment. This in vitro study was performed to investigate the reverse transfer of soluble Pseudomonas aeruginosa ba cterial products across a polyether sulfone (PES), a newly developed s ynthetic polymer dialyzer, In vitro dialysis was carried out at 37 deg rees C in a closed countercurrent recirculating loop dialysis circuit with a new PES dialyzer. An equal mixture of heparinized whole blood ( from healthy volunteers) with pyrogen-free tissue culture medium was c irculated in the blood compartment, and bicarbonate dialysate was circ ulated in the dialysate compartment. After 15 min of dialysis, the dia lysate was challenged sequentially with 10(-4), 10(-3), and 10(-2) dil utions of a P. aeruginosa culture supernatant, 1-ml samples were drawn From the blood compartment 5 and 15 min after each challenge and incu bated upright at 37 degrees C. At the end of 24 h, Triton-X-100 was ad ded, in order to extract total interleukin (IL) 6 and IL-8 production by the whole-blood mixture. These cytokines were measured by electroch emiluminescence assays. At dilutions of 10(-4) and 10(-3), the reverse transfer of soluble bacterial products across the dialyzer was neglig ible. Five and 15 min after contaminating the dialysate with the highe st concentration (10(-2) dilution), the increase in IL-6 production wa s 239 +/- 170% (p = 0.06) and 886 +/- 444% (p = 0.02), respectively. H owever, comparing the IL-6-inducing potency of the 10(-2) bacterial su pernatant dilution to the spontaneous IL-6 production in the brood com partment during dialysis with the same dilution of dialysate contamina nt, there was a dramatic reduction in IL-6 production by 94 and 89% at 5 and 15 min, respectively, Similarly 5 and 15 min after contaminatin g the dialysate with the 10(-2) dilution, the increase in IL-8 product ion was 357 +/- 147% (p = 0.07) and 630 +/- 229% (p = 0.04), respectiv ely. However, comparing the IL-8-inducing potency of the 10(-2) bacter ial supernatant dilution to the spontaneous IL-8 production in the bro od compartment during dialysis with the same dilution of dialysate con taminant, there was a dramatic reduction in IL-8 production by 93 and 92% at 5 and 15 min, respectively, These results demonstrate that PES dialyzers markedly attenuate passage of cytokine-inducing substances f rom contaminated dialysate, using a method that detects the entire cyt okine synthetic output in the blood compartment.