The authors devised a method to enhance delivery of vinblastine to macrophages, the cells believed to be responsible for platelet destruction in idiopathic thrombocytopenic purpura. The authors' strategy was based on the ability of platelets to bind vinca alkaloids such as vinblastine. Platelets were incubated with an excess of vinblastine, concentrated and then, after the excess alkaloid had been removed, given to 11 patients with idiopathic thrombocytopenia refractory to other treatment (including intravenous injections of vinca alkaloids). Platelet antibodies in the patients' plasma led to ingestion of the vinca-laden platelets by macrophages. There were 6 complete remissions, 3 partial remissions and 2 failures. Side effects in a few patients, reversible but annoying, were minimized as technics were refined. The authors conclude that in patients with idiopathic thrombocytopenia refractory to all other measures, including the use of vinca alkaloids, platelet-vinca complex may be effective.
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