VWF MM ratio, VWF antigen, ADAMTS13 activity, and ADAMTS13 CI in patients with iTTP. The VWF MM ratio (A), ADAMTS13 activity (B) and VWF antigen (C) in 82 patients with iTTP with and without acute episodes during the study period, as well as in 65 controls. On the left side of panels A, B, and C, the VWF MM ratio, ADAMTS13:act, and VWF:Ag values are shown before (n = 14), at the beginning (n = 16) as well as in remission after the acute episode (n = 20). On the middle panel, patients with iTTP who were constantly in remission are grouped according to ADAMTS13 values <10% (n = 13) and ≥10% (n = 54). An open ADAMTS13 conformation is marked with red symbols, and a closed one is marked with blue symbols in panels A-C. Controls are shown on the right side of panels A and C. Gray background is the normal range of the VWF MM ratio assessed in controls.