CYTOKINE PRODUCTION AND PROTEIN ADSORPTION IN A STAINLESS-STEEL FILTER USED FOR LEUKOCYTE REDUCTION

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, ads orbed proteins on each fiber were identified by using sodium-dodecyl s ulfate (SDS)-polyacrlyamide gel electrophoresis (PAGE). The levels of tumor necrosis factor (TNF)-alpha 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, respe ctively. The levels of interleukin (IL)-1 beta 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-tau levels were less than 7.8 pg/ ml in all three conditions. The amount of adsorbed proteins was 3.39 /- 0.27 mu g/cm(2) for the polyester fibers and 2.72 +/- 0.23 mu g/cm( 2) for the stainless steel fibers. The protein bands adsorbed to the p olyester fibers by SDS-PAGE analysis were observed at approximately 18 0, 120, 90, 76, 67, 59, 56, and 28 kd molecular weight. In contrast, t he protein bands adsorbed to the stainless steel fibers were observed at 90, 76, 67, 62, 56, 28, and 12 kd molecular weight. Thus, the prote ins adsorbed to the stainless steel fibers differed from those on the polyester fibers. By western blot analysis, the amounts of albumin, Ig G tau chain, and fibronectin adsorbed on the stainless steel fibers we re smaller than those on the polyester fibers. The results of this stu dy suggest that the stainless steel fibers do not stimulate monocytes, Th 1, and Th2 cells. In addition, lesser adsorption of IgG tau chain and fibronectin may indicate that the stainless steel is a superior ma terial for anti thrombogenicity compared to polyester.