*These authors contributed equally to the manuscript.
Predicting response to plasma exchange in patients with thrombotic thrombocytopenic purpura with measurement of vWF-cleaving protease activity
Article first published online: 19 JUN 2002
Volume 42, Issue 5, pages 572–580, May 2002
How to Cite
Mori, Y., Wada, H., Gabazza, E. C., Minami, N., Nobori, T., Shiku, H., Yagi, H., Ishizashi, H., Matsumoto, M. and Fujimura, Y. (2002), Predicting response to plasma exchange in patients with thrombotic thrombocytopenic purpura with measurement of vWF-cleaving protease activity. Transfusion, 42: 572–580. doi: 10.1046/j.1537-2995.2002.00100.x
HUS = hemolytic-uremic syndrome; PE = plasma exchange; TTP = thrombotic thrombocytopenic purpura; UL-vWFM(s) = unusually large vWF multimer(s); vWF-CPase = vWF-cleaving protease.
Supported in part by research grants from the Japanese Ministry of Health and Welfare for Cardiovascular Diseases (Y.F.) and from the Japanese Ministry of Education Culture and Science (Y.F.).
- Issue published online: 19 JUN 2002
- Article first published online: 19 JUN 2002
- Received for publication June 2, 2001; revision received December 24, 2001, and accepted December 29, 2001.
BACKGROUND: Severe deficiency of vWF-cleaving protease (vWF-CPase) activity was recently found in patients with thrombotic thrombocytopenic purpura (TTP). Although the survival of patients with TTP has been dramatically improved with plasma exchange (PE), there are still many patients who are refractory to PE and immunosuppressive therapy.
STUDY DESIGN AND METHODS: The activities of vWF-CPase and its inhibitor were measured in 27 patients with nonfamilial TTP and hemolytic-uremic syndrome (HUS) to examine the relationship between the clinical variables and vWF-CPase activity.
RESULTS: Eight of nine patients with HUS had more than 40 percent of vWF-CPase activity, whereas one had 28 percent of the normal level at the acute phase. Ten of 12 TTP patients with a good outcome had a severe deficiency of vWF-CPase activity and its inhibitor, whereas four of six patients with a poor outcome had a moderate deficiency of vWF-CPase activity along with a lack of the inhibitor. PE produced normalization of the vWF-CPase activity and neutralization of the inhibitor in TTP patients with a good outcome; however, some TTP patients with vWF-CPase inhibitor had relapsed and required an immunosuppressive therapy. The response to the combination therapy with PE and immunosuppressive treatment was poor in TTP patients without a severe deficiency of vWF-CPase activity.
CONCLUSION: Assays of vWF-CPase activity and its inhibitor may be useful for predicting the response to therapy and the outcome of patients with TTP. In some patients, nonfamilial TTP with a poor prognosis may not be caused by a constitutional or acquired deficiency of vWF-CPase with its inhibitor. Although PE and immunosuppressive therapy are effective in patients with nonfamilial TTP and a vWF-CPase inhibitor, other therapeutic modalities may be needed for nonfamilial TTP with unknown etiology.