A new metallic filter made from a stainless steel fiber has been under development. To evaluate biocompatibility of this filter, the authors compared cytokine production with that of stainless steel fibers and polyester fibers by using a mononuclear cell culture. Furthermore, adsorbed proteins on each fiber were identified by using sodium-dodecyl sulfate (SDS)-polyacrlyamide gel electrophoresis (PAGE). The levels of tumor necrosis factor (TNF)-α in the cultured supernatant without fibers as the control, with polyester fibers, and with stainless steel fibers were 28.1 ± 8.1, 39.3 ± 2.6, and 29.1 ± 6.7 pg/ml, respectively. The levels of interleukin (IL)-1β were 7.6 ± 3.2, 8.9 ± 1.5, and 8.9 ± 2.1 pg/ml, respectively. The IL-4 levels were less than 0.25 pg/ml, and the interferon-± levels were less than 7.8 pg/ml in all three conditions. The amount of adsorbed proteins was 3.39 ± 0.27 ng/cm2 for the polyester fibers and 2.72 ± 0.23 μg/cm2 for the stainless steel fibers. The protein bands adsorbed to the polyester fibers by SDS-PAGE analysis were observed at approximately 180, 120, 90, 76, 67, 59, 56, and 28 kd molecular weight. In contrast, the protein bands adsorbed to the stainless steel fibers were observed at 90, 76, 67, 62, 56, 28, and 12 kd molecular weight. Thus, the proteins adsorbed to the stainless steel fibers differed from those on the polyester fibers. By western blot analysis, the amounts of albumin, IgG °Chain, and fibronectin adsorbed on the stainless steel fibers were smaller than those on the polyester fibers. The results of this study suggest that the stainless steel fibers do not stimulate monocytes, Th1, and Th2 cells. In addition, lesser adsorption of IgG °Chain and fibronectin may indicate that the stainless steel is a superior material for anti thrombogenicity compared to polyester.
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