Late response to cyclosporine in refractory thrombotic thrombocytopenic purpura.

Plasma exchange (PEX) with fresh frozen plasma, usually in association with steroid therapy, has been shown to be the first-line treatment of thrombotic thrombocytopenic purpura. It works by removing ultralarge von Willebrand factor (vWF) multimers and inhibitory antibody and by supplying normal protease. For patients with disease refractory to PEX, there is no standardized treatment.