Clinical response in patients with idiopathic TTP, severe ADAMTS13 deficiency, and a high-titer inhibitor. ADAMTS13 inhibitor screen was positive on the initial plasma samples prior to plasma exchange therapy and inhibitor titer was determined. All patients represented in this figure had inhibitor titer of more than 5 units/mL on presentation. The thick solid bar indicates daily plasma exchange; and thick dashed bar, tapering of plasma exchange. Other adjunctive therapies were given during the period of observation as indicated. However, patient 10 had a more than 10-year history of TTP and received plasma exchange (PEx) in addition to prednisone (P), splenectomy (S), and a combination of prednisone, vincristine, and cyclophosphamide (CVP) prior to this admission. Patient 12 was reported previously³³  and whose therapies with splenectomy (S), vincristine (V), rituximab (R), and rituximab plus cyclophosphamide (R+) are shown as indicated. Patient 13 received only plasma exchange and prednisone and is in remission.