Hemodialysis filter fibers induce complement activation and enhance TF-dependent procoagulant properties in normal and ESRD sera. (A) The amounts of C3 cleavage products in plasma isolated from normal nontreated blood (bar 1), nontreated blood incubated in 37°C for 60 minutes (bar 2), blood treated with filter fibers (bar 3), or blood treated with filter fibers in the presence of compstatin analog (bar 4) or control peptide (bar 5). Data are representative of 4 independent experiments (mean ± SD). The paired t test was used to assess statistical significance: *P < .05. (B) The mPT values of supernatants of normal PMNs incubated with sera from healthy donors (HI, bar 1), sera activated with filter fibers for various periods of time (bars 2-5), or with filter fiber-activated sera (for 60 minutes) and treated with TF monoclonal antibodies (bar 6). Data are representative of 6 independent experiments (mean ± SD). The Wilcoxon matched-pairs test was used to assess statistical significance: *P < .01. (C) The mPT values of supernatants of normal PMNs incubated with sera from healthy donors (HI, bar 1), ESRD patients before hemodialysis (predialysis [Pred], bar 2), filter fiber-activated sera from healthy donors or patients (bars 3 and 6, respectively), sera from healthy donors or patients incubated with these fibers in the presence of compstatin analog (bars 4 and 7, respectively) or pretreated with C5aR antagonist and then incubated with fiber-activated sera from healthy donors or patients (bars 5 and 8, respectively). Data are representative of 6 independent experiments (mean ± SD). The Wilcoxon matched-pairs test was used to assess statistical significance: *P < .01. (D) The induction of TF expression in normal PMNs incubated with sera from healthy donors (bar 1), fiber-activated sera (bar 2), or sera treated with fibers in the presence of compstatin analog (bar 3). The results are presented as ratios of the mean fluorescence intensities (MFI) of the cells incubated with sera treated with fibers in the presence or absence of compstatin to the cells incubated with sera from healthy donors, stained with TF monoclonal antibodies, and analyzed by flow cytometry. Data are representative of 6 independent experiments (mean ± SD). The Wilcoxon matched-pairs test was used to assess statistical significance: *P < .05. (E) TF expression in normal PMNs incubated with PBS (1), APS sera (2), fiber-treated sera in the presence of compstatin analog (3), or fiber-activated (4) or untreated sera (5). One representative Western blot analysis of 4 independent experiments is shown. Horizontal lines above data bars indicate statistical significance.