Thrombotic Thrombocytopenic Purpura (TTP) is a rare hematologic emergency, congenital or acquired, characterized by ischemic damage of various organs because of platelet aggregation. It is the common name for adults with microangiopathic hemolytic anemia, thrombocytopenia, with or without neurologic or renal abnormalities, and without another etiology; children without renal failure are also described as TTP. Plasma exchange (PE) is the main stay of treatment in combination with steroids and immunosuppressive therapies. The monoclonal antibody against CD20 Rituximab decreases the production of antibodies from B lymphocytes and it is used for antibodies-mediated diseases including TTP. We present our data on retrospective analysis of rituximab in treatment of TTP at University of Cincinnati in a series of 22 patients from 1997 to 2009. Our results showed that PE with immunosuppressive therapy resulted in decreased duration of PE, relapse rate, and increased duration of remission in patients with TTP. 1. Introduction TTP is a rare hematologic emergency in which various organs, mainly the brain and kidneys, are affected by ischemic damage due to platelets aggregations. It is characterized by thrombocytopenia, MAHA, fever, and neurological and renal abnormalities; however, this pentad is not necessary for diagnosis. TTP may be congenital or acquired as a result of HIV, connective tissue disorder, cancers, drugs like quinine, mitomycin C, cyclosporine, oral contraceptives, and ticlopidine or it may be idiopathic. Only thrombocytopenia and MAHA without another clinically apparent etiology (e.g., disseminated intravascular coagulation, malignant hypertension, severe preeclampsia, sepsis, and systemic malignancy) are required to suspect the diagnosis of TTP and to initiate PE. MAHA is defined as nonimmune hemolysis (i.e., negative direct antiglobulin test) with prominent red cell fragmentation (schistocytes) observed on the peripheral blood smear. The pathogenesis may be autoimmune in nature since autoantibodies against ADAMTS13 (acronym for a Disintegrin and a Metalloproteinase with Thrombospondin-1 Motifs, 13th member of the family), which cleaves von Willebrand Factor (vWF), are typically present in most cases of idiopathic TTP. These antibodies cause the absence of ADAMTS 13 protease activity and the persistence of vWF. Subsequently the procoagulation tendency dominates and causes the systemic abnormalities. The mainstay of treatment for patients with TTP is PE in conjunction with steroids. The mortality rate of TTP prior to the use of PE was approximately
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