 The study has been designed to cause the least disruption and inconvenience to patients and their standard and treatmentcare. It is imperative that patients are continuously assessed and monitored during and post study treatment. Any potential risk is offset by i improving time to remission, associated with a decreased time of active TTP and organ damage, ii reduced exposure to plasma products and thus the risk of vCJD and iii improved management of acute TTP and mortality of these patients. 