Open ADAMTS13 Conformation in Immune-Mediated Thrombotic Thrombocytopenic Purpura Is Induced By Anti-ADAMTS13 Autoantibodies and Corresponds with an Ongoing ADAMTS13 Pathology

Background. Deficient ADAMTS13 activity (TS13:act <10%) induced by anti-ADAMTS13 autoantibodies (autoAbs) causes immune-mediated thrombotic thrombocytopenic purpura (iTTP). Recently we showed that an open ADAMTS13 conformation is characteristic for acute iTTP patients, while folded ADAMTS13 was found in 78% of iTTP patients in remission with an TS13:act >50%. However, also iTTP patients in remission with a persistent (<10%) or...