 Rituximab licensed and internationally used monoclonal antibody selectively acts on white blood cells known as B-lymphocytes or B cells that produce the antibody to ADAMTS 13. By inhibiting ADAMTS 13 antibody production, ADAMTS 13 activity increases, resulting in remission. Rituximab has been used in our institutions in patients with acute TTP that are refractory to standard treatment - PEX. The resulting remission has been dramatic, with a non-toxic side effect profile and no patients to date has relapsed longest follow-up 19 months following Rituximab therapy. Therefore, we plan to use Rituximab with PEX in patients who present with acute TTP. 