Caplacizumab also prevents the formation of NETs 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, with or without caplacizumab (3 μg/mL). (C-D) The rate of thrombus formation (mean ± SEM) (n = 3) as a function of time in the blood samples of iTTP on admission and after treatment, respectively, under flow with or without caplacizumab. (E-F) Representative microscopic images show the staining of 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 caplacizumab, after fixation and restaining with anti-CD41 and SytoxGreen. (Ei-Fi) Enlarged areas (5×) from E and F, respectively, indicate extracellular DNA strings, platelets, and neutrophils. (G-H) The number of elongated DNA strings (mean ± SEM) (n = 3) formed at the end of perfusion of whole blood samples from patients with iTTP on admission and after treatment with or without caplacizumab. The data shown are median (bar) and IQR. Mann-Whitney test was used for the differences between the 2 groups. Capla, caplacizumab; N, neutrophil; PLT, platelet; n.s. and ∗∗ indicate P > .05 and P < .01, respectively.