Abstract
Summary
The presence of a factor in patients with the myeloproliferative syndrome that enhances the effect of erythropoietin on the EP-responsive stem cell was evaluated in hyper-transfused mice. The serum of four patients with agnogenic myeloid metaplasia and four of five patients with polycythemia Vera significantly increased the effect of a standard dose of EP. The serum of four patients with chronic granulocytic leukemia and one patient with idiopathic leukocytosis failed to enhance the response to EP. The enhancing effect could not be ascribed to EP in, the injected serum. Evidence is presented that the serum factor either expands the number or increases individual sensitivity of the EP-responsive stem cells. Failure to find this factor in chronic granulocytic leukemia suggests a different control mechanism in leukemia from the other myeloproliferative disorders.
Get full access to this article
View all access options for this article.