Bone Marrow Response to Erythropoietin in Polycythemia

The regulation of erythropoiesis was control cultures. Erythropoietin was studied in patients with polycythemia ineffective in stimulating iron incorpovera and chronic granulocytic Ieukeration into heme in five patients with mia (CGL). An in vitro culture system polycythemia vera. The marrow rewas employed to determine the response to erythropoietin in vitro was sponse of bone marrow cells to erythwithin the normal range in three paropoietin. In normal subjects, iron tients with CGL (37#{176}/o stimulation). incorporation into heme (during the Thus, the role of erythropoietin in the 18th to 22nd hr of culture) was incontrol of erythropoiesis in myeloprocreased by 35#{176}/o (mean) in erythropoliferative syndromes appears variable. ietin-treated cultures as compared to E RYTHROI’OIETIN IS AN IMPORTANT HORMONE in the physiologic control of erythropoiesis. It increases erythropoiesis by inducing primitive cells to differentiate into erythroblasts that subsequently mature and form nonnucleated red cells.’ 3 In contrast to polycythemia secondary to hypoxia, erythropoietin does not appear to be responsible for the increased red cell production in polycythemia vera. This is suggested by the following observations: urine and serum erythropoietin levels are normal or decreased in polycythemia vera,4’5 and erythropoietin added to in vitro marrow cultures from patients with polycythemia vera fails to elicit any stimulatory effect.67 Chronic granulocytic leukemia is a panmyelopathy and, in that respect, resembles polycythemia vera. Both have therefore been classified as myeloproliferative diseases.8 The purpose of this study was to determine whether erythropoietin was capable of stimulating erythropoiesis in marrow cultures obtained from patients with chronic granulocytic leukemia as compared to polycythemia vera.