Circulating microparticles of PNH patients express endothelial markers: intercellular adhesion molecule 1 (ICAM-1), soluble vascular cell adhesion molecule-1 (sVCAM-1), von Willebrand factor, CD144 (VE-cadherin), indicating chronic endothelial activation and vascular inflammation.33,34 Eculizumab (a monoclonal antibody to complement protein 5) therapy results in rapid and sustained decreases in markers of inflammation, thrombin generation, and TF-bearing microparticles in PNH patients.35 Here, ICAM1 is linked to paroxysmal nocturnal hemoglobinuria.