Clinical features of TTP induced by anti-ADAMTS13 antibody in a baboon. (A) The development of sustained, severe thrombocytopenia after 2 infusions of anti-ADAMTS13 antibody (circles, with infusions indicated by arrows; squares represent infusion of a control immunoglobulin). (B) The development of microangiopathic hemolytic anemia in the affected baboons (narrow arrowheads indicate schistocytes; broader arrowheads indicate polychromatophilic red cells). (C) A section of brain with a capillary thrombus (hematoxylin and eosin stain; special stains documented that the thrombus contained platelets and VWF). Professional illustration by A. Y. Chen.