Recombinant ADAMTS13 prevents NET formation under flow in iTTP. (A-B) Representative images illustrating the final coverage of neutrophils and platelets on a collagen-coated surface following perfusion of whole blood samples from iTTP on admission and after therapy, respectively, with or without recombinant ADAMTS13 (6 μg/mL) under flow. (C-D) The rate of thrombus formation (mean ± SEM) as a function of time after perfusion of whole blood samples of iTTP on admission and following treatment, respectively, with or without rADAMTS13 under flow. (E-F) Representative confocal fluorescent images show platelets (purple), neutrophils (green), and extracellular DNA strings (elongated green) following perfusion of whole blood samples from iTTP on admission and following therapy, respectively, with or without rADAMTS13, following fixation and restaining. (Ei-Fi) Enlarged areas (5×) from E and F, respectively, indicate extracellular DNA strings, platelets, and neutrophils, respectively. (G-H) The number of elongated DNA strings formed at the end of perfusion of whole blood samples from iTTP on admission and following therapy, respectively, with or without rADAMTS13 (n = 5). The data shown are median (bar) and IQR. Mann-Whitney test was used for the differences. n.s. and ∗∗ indicate P > .05 and P < .01, respectively. rA13, recombinant ADAMTS13; N, neutrophil; PLT, platelet; SEM, standard error of the mean.