Amount of circulating microparticles in peripheral blood samples from 26 control subjects, 8 AA individuals without a PNH clone (AA), 17 AA individuals with a PNH clone (AA/PNH), and 12 PNH patients. The particle capture procedure involving insolubilized AV as well as the assay of their phosphatidylserine content based on the ability of this phospholipid to promote the assembly of the clotting prothrombinase enzyme complex are detailed in Aupeix et al.11 The mean ± SD for the control group is 5.3 ± 2.2 nmol/L phosphatidylserine equivalent, that of the AA group is 1.9 ± 1.6 nmol/L, that of the AA/PNH group is 11.1 ± 9.1 nmol/L, and that of the PNH group is 14.4 ± 10.5 nmol/L phosphatidylserine equivalent. P values reflect the significance of the patients’ circulating particle levels compared with healthy controls or patients from other indicated groups. Statistical analysis was performed using the Student’s two-tailed t-test.