Effect of artificial surface-induced complement activation on the hemostatic system in whole blood. FPX-anticoagulated blood was incubated for 0, 30, or 120 minutes at 37°C in the presence or absence of Cp40 (20 μM) and assessed for (A) platelet count and (B) global coagulatory parameters (prothrombin time [PT] and partial thromboplastin time [aPTT]). (C) The generation of thrombin/antithrombin complexes was measured in EDTA-treated plasma via ELISA. (D-E) EDTA-treated plasma derived from the whole blood reactions was analyzed for the concentrations of the soluble platelet activation markers CD40L and von Willebrand factor. (F) The activation status of platelets in whole blood was determined by CD62P surface expression using flow cytometry. After the indicated incubation time, blood was exposed for 10 minutes either to PBS (negative control [neg. Ctrl]) or ADP (5 μM). All graphs show mean values with standard deviation of at least 4 independent assays. For all panels, the mean values of at least 4 independent assays ± standard deviation are shown. Data sets were tested for outliers using the ROUT outlier test (Q = 5%). Data sets were either analyzed using either Prism mixed-effects model (in case of missing values) or repeated measures one-way ANOVA. Experimental groups were post hoc tested for statistical significance against the 120 minutes + Cp40 group with Dunnett correction for multiple comparisons (panels A-E) or against each other experimental group (Tukey test with correction for multiple comparisons). For the sake of visibility, nonsignificant P values were omitted from graphs, unless they were of relevance to the experimental hypotheses.