ADAMTS13 activity and CIND. (A) Analysis of ADAMTS13 activity and CIND in remission. ADAMTS13 activity is plotted against CIND and includes samples at diagnosis (n = 98) and remission (n = 119). ADAMTS13 activity >60% and <60%, and CIND >0.5 and <0.5 are shown. A CIND >0.5 is considered an open conformation, indicative of the presence of autoantibodies. The right upper quadrant shows samples with an open conformation, despite ADAMTS13 activity >60%. (B) Proportion of patients with open and closed conformations when comparing peak and nonpeak ADAMTS13 activity in remission. Most patients with peak ADAMTS13 activity had a closed ADAMTS13 conformation.