Endothelium damage triggers the multimeric protein von Willebrand factor (VWF) release and subsequent binding to platelets, which are recruited at sites of vascular injury. A complex and fragile equilibrium between circulating levels of von Willebrand factor and its metalloprotease, ADAMTS13, is responsible for the hemostatic balance. However, the presence of autoantibodies targeting ADAMTS13 results in an increase in von Willebrand factor, mainly in its ultra-large multimers. The latter lead to platelet aggregation, the formation of thrombi and microangiopathic hemolytic anemia. This pathologic condition, known as immune-mediated thrombotic thrombocytopenic purpura (iTTP), occurs with high morbidity and a high rate of relapses. In this work, the long-term follow-up of 40 patients with iTTP is reported. We assessed ADAMTS13 activity, plasmatic VWF levels and the ADAMTS13/VWF ratio, comparing iTTP relapsing patients with remitting ones. A decrease in the ADAMTS13/VWF ratio, along with a reduced ADAMTS13 activity, could serve as predictive and sensitive biomarkers of incoming relapses.
Keywords: ADAMTS13; ADAMTS13/VWF ratio; biomarker; laboratory diagnostics; thromboinflammation; thrombosis; thrombotic thrombocytopenic purpura (TTP); von Willebrand factor.