PMNs from patients with PNH exhibit an impaired transendothelial migration. (A) PMNs were seeded on HUVEC monolayers grown on fibronectin-coated transwell filters. Migration is shown in the presence of a 10-nM fMLP transwell gradient. Transmigration assays of PMNs from patients with PNH (□) and from healthy donors (▪) were run in parallel and the percentage of transmigrated cells was evaluated after 1 and 2 hours. Data are expressed as the mean ± SD of 4 separate experiments. *P < .001. (B) Summary of the results of transendothelial migration of neutrophils from 7 patients with PNH (○) analyzed in parallel with 13 healthy donors (•). The percentage of transmigrated cells in the presence of a 10-nM fMLP transwell gradient was evaluated after 1 hour. The number enclosed in parentheses indicates the percentage of CD157⁺ PMNs. Horizontal bars indicate the mean value of transmigration.