Studies on the Erythropoiesis Inhibiting Factor in the Plasma of Animals with Transfusion Polycythemia

Further investigations of the action of polycythemic plasma filtrate were madeusing Fe⁵⁹ and with detailed examination of the blood and bone marrow. Thesestudies confirmed the appearance of an active thermostabile plasma factor(erythropoiesis inhibitor) which depressed erythropoiesis in normal rabbits orrats. The plasma obtained from bilaterally nephrectomized sheep subjectedto transfusion polycythemia also contained the erythropoiesis inhibitor. Blockade of the reticuloendothelial system using trypan blue, in sheep, inducedproduction of the active substance similar or identical with the erythropoiesisinhibitor produced after transfusion polycythemia.

Submitted on November 2, 1960 Accepted on October 10, 1961