La sterilizzazione a vapore del polisulfone low-flux riduce la produzione monocitaria di citochine in emodialisi

This study was undertaken to verify whether hemodialysis induced cytokine production is influenced by the membrane sterilization technique. Sterilization of a low-flux polysulfone membrane (1.3 m²) with steam (F6- HPS Fresenius AG) or with (ETO) ethylene oxide (F6 Fresenius AG) was compared in six patients undergoing regular hemodialysis treatment. After three months of dialysis with F6, a basal test was performed (A1); the same was set up after 1 (B1) and 2 (B2) months of F6-HPS treatment; the last one after 1 month after return to F6 (A2). For each test blood was drawn pre and post- dialysis and was analyzed for: IL-1 beta and TNF alpha release after 24h incubation of mononuclear cells (MN) (ELISA, pg/ml/10x6 MN); C3a and C5a levels were assessed at 0' 5' 15' and 60' in each test. Microbial dialysate contamination was tested with LAL-test. Anti-ETO IgE antibodies were checked in A1, B2 and A2 by RIA. LAL-test showed a good quality of the dialysate throughout the study. Spontaneous IL-1 and TNF production by MN was 215 and 359 respectively in A 1 (pre-HD); it showed a sharp and significative reduction both in B1 (49 and 157, p=0.01) and in B2 (54 and 89, p=0.01); moreover, a significative rebound was observed in A2 (284 and 463, p=0.01). Post-dialysis data showed the same pattern. There was no significative difference between pre and post-HD levels in each test; no correlation was found between cytokine release and LAL-test results. C3a and C5a release did not show any significative changes. Anti-ETO IgE antibodies were not detected in any patient. Dialysate contamination being excluded, MN cytokine production was significantly lowered by steam sterilization membrane. Although the mechanisms are not clear (effect of steam on biomaterial surface or ETO residual) our data indicate that the sterilization method plays a role in the complex phenomenon of membrane biocompatibility.