Sterilizzazione del cuprophan con vapore ed ossido di etilene: Relazione con la produzione linfomonocitaria di citochine

The side effects of ethilene oxide support the use of steam as the best sterilization procedure for medical devices. However, still now the effects of steam on mononuclear cytokine release, if any, are unknown. We enrolled 8 patients on chronic hemodialysis free from neoplastic, allergic or connective diseases, and compared the ETO and steam sterilization of cuprophan membrane (E3 and E3S, 1,3 m² Fresenius AG). After a 3-month dialysis period with E3, a basal test was set up (A1); the same was performed after one-(B1) and two- (B2) month E3S treatment; finally, the last test was performed one month after the return to E3 (A2). In each test pre- and post dialysis samples were drawn for: LAL-test, to exclude dialysate contamination; IL-1β and TNF-α release after a 24-h incubation of mononuclear cells (MN) (ELISA pg/ml/10⁶ MN); C3a and C5a levels at 0, 5', 15' and 60' to evaluate complement activation. LAL-test showed good quality of the dialysate through the study, and C3a and C5a levels were not different. Spontaneous release of IL-1β and TNF-α by MN was 162 and 826 pg/ml respectively in A1; it showed a clearly increase either in BI and B2 (185 and 226 for IL-1β and 720 and 1970 for TNF-α). The return to E3 showed a decrease in the cytokine release (123 and 689 pg/ml, respectively). Thus, steam sterilization seems to induce a higher cytokine release by MN when a cuprophan membrane is used. Dialysate contamination and a different complement activation being excluded, the only cause of the different cytokine production is the sterilization method. These results underlined the great complexity of the biological interactions of medical devices.