Abstract
Ethylene oxide (ETO) is presently the most commonly used sterilization method for medical devices. Although alternative sterilization modes such as steam sterilization have been suggested, the effect of steam on dialysis-induced cytokine release is unknown.
We enrolled 9 patients on chronic hemodialysis and evaluated at different intervals IL- 1βproduction while treated with ETO (NC1785–Bellco) and steam sterilized NC 1785S-Bellco) Synthetically Modified Cellulose (SMC). A basal test during treatment with NC 1785 was performed (A); the same test was set up 4 weeks after treatment with NC 1785S (B) and, lastly, 4 weeks after returning to NC 1785 (C). Peripheral blood mononuclear cells (PBMC) were purified before and after the dialysis session, were isolated on a Ficoll/Hypaque gradient and incubated for 24 h. Spontaneous IL-1β release was evaluated in the supernatant and in the lysate.
In A, IL-1βlevels were (in pg/ml/106 cells, in supernatant and lysate, respectively): 5.8 ± 4.8 and 7.6 ± 5.2 in pre-HD and 4.68 ± 3.6 and 9.7 ± 6.65 in post-HD. These levels showed a clear reduction in B: 2.5 ± 2.2 and 4.4 ± 3.1 in pre-HD, and 4.35 ± 6.6 and 7.52 ± 7.22 in post-HD. In the C test, 4 weeks after the return to the ETO membrane, IL-1βlevels remained unchanged: 2.9 ± 1.8 and 4.5 ± 3.1 in pre-HD; and 2.6 ± 3 and 5.7 ± 6.6 in post-HD. Statistical analysis showed significant changes in the pre-HD levels both in supernatant (p < 0.04) and in lysate (p < 0.04).
Steam sterilization of SMC induced a lower spontaneous IL-1β release, but this effect was not statistically significant due to the large inter-individual variation. Hence, contrary to claims of better biocompatibility, steam sterilization does not result in a reduced production of pro-inflammatory IL-1β.
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