 Given the significant benefit in terms of remission, the increased level of ADAMTS 13 level in patients with acute refractory TTP and documented benefit of patients with other antibody driven disorders with Rituximab therapy, Rituximab in conjunction with standard therapy - PEX, is to be investigated. This is to reduce mortality further that the 15-20, reducing the number of PEXs and therefore decreasing the exposure to blood component products that may contain fatal proteins such as variant Creutzfeldt-Jakob Disease vCJD. As between 30-60 relapse with a further episode of TTP, follow up to determine time to relapse will be observed and compared to historical controls. During this period, blood counts and ADAMTS 13 levels will be assessed. We have a specific assay to determine the benefit following treatments and historical data to compare previous patient admission that can be matched. Researcher bias will be reduced as the time taken for a specific platelet level count 150 x 10 to the power of 9L must be determined and recorded within the routine laboratory in each institution, the number of PEX will be recorded by the patients nurse, continuing until the platelet count is maintained above 150 x 10 to the power of 9L. In addition, there will be a clear audit trail, which will allow data and records to be cross checked. 