Thrombotic thrombocytopenic purpura consists of thrombocytopenia, microangiopathic hemolytic anemia, fluctuating neurologic signs, fever, and renal impairment [1]. The primary treatment modality is plasmapheresis, which is sometimes combined with antiplatelet therapy [2]. Splenectomy and immunosuppressive therapy have been used where the response is poor [2, 3].

We describe a 64-year-old man in whom the disease was controlled by cyclosporine after plasmapheresis failed. When admitted, he was in a confused state and had an unexplained fever (temperature, 39.1 °C), a slightly enlarged liver, a hemoglobin concentration of 97 g/L, a platelet count of 31 000/mm³, red cell fragmentation (25% of all erythrocytes), proteinuria, and hematuria. Creatinine (250 µmol/L), urea (14 mmol/L), bilirubin (69 µmol/L), and lactic dehydrogenase (1500 IU/L; normal range, 80 to 240 IU/L) levels were increased. No autoantibodies were detected. Coombs tests were negative; disseminated intravascular coagulation was excluded. Thrombotic thrombocytopenic purpura was diagnosed, and treatment was begun with a 3-litre plasma exchange every second day. In addition, aspirin, dipyridamole, and prostacyclin were administered. No stable remission could be achieved, and after day 15 treatment was ineffective.

On day 20, conventional therapy was discontinued and cyclosporine, 300 mg/d, was instituted. Therapeutic blood levels were attained within 3 days, and complete remission occurred within 8 days. Cyclosporine therapy was continued for 3 months and stopped by the patient.

Three months after discontinuing cyclosporine treatment, the patient had a relapse that was characterized by thrombocytopenia (40 000/mm³), anemia (hemoglobin, 90 g/L), neurologic symptoms, and an increased creatinine level. Cyclosporine (300 mg/d) was administered as the sole therapy, and complete remission was achieved within 10 days. The patient has been in full clinical and hematologic remission for 9 months on cyclosporine (Figure 1). Although plasmapheresis has reduced the mortality associated with thrombotic thrombocytopenic purpura, it is not universally effective, either alone or in combination with antiplatelet agents [2, 3]. Because some patients with thrombotic thrombocytopenic purpura have cytotoxic antibodies, immunosuppressive agents such as prednisolone, azathioprine, vincristine, cyclophosphamide, and immunoglobulins have been used empirically for the proposed immunologic damage [3-5].

View larger version (18K): [in this window] [in a new window]   Figure 1. Platelet count and lactic dehydrogenase (LDH) activity during both conventional treatment (C.T.), including plasma exchange, aspirin, dipyridamole, and prostacyclin; and cyclosporine treatment.

Cyclosporine alone appears to have induced a remission in one patient with thrombotic thrombocytopenic purpura resistant to conventional therapy and was also effective when the patient experienced a subsequent relapse. In contrast to other immunosuppressive therapy, cyclosporine has fewer side effects and may prove to be a useful alternative therapy for patients with chronic thrombotic thrombocytopenic purpura.