Effects of protein C on neutrophil migration. Deactivation of directional migration of neutrophils by protein C (A), activated recombinant human protein C (ArhPC) (B), and activated plasmatic human protein C (AphPC) (C). Experiments were performed in modified Boyden chambers using nitrocellulose micropore filters. Cells were preincubated with varying PC/APC concentrations for 20 minutes, followed by washing. Then chemotaxis toward IL-8 (1 nM), AT (1 U/mL), fMLP (10 nM), or C5a (10 nM) was monitored. Results are given as the mean ± SEM of the migration index, which is the ratio of the distance of migration (μm) toward attractant and that toward medium. Random migration in the absence of an attractant gradient was 50.780 ± 1.588 μm(n = 42). *P < .05, Mann-Whitney U test versus medium incubation after multiple group comparison by Kruskal-Wallis test. n = 3 (except for protein C-C5a, ArhPC-IL8, fMLP; n = 5).