Erythropoietin responsiveness in polycythaemia vera.

A liquid bone marrow culture technique was used to study erythropoiesis in polycythaemia vera. Three patients with the diagnosis of polycythaemia vera treated only by phlebotomy were compared to three healthy volunteers. Erythropoiesis in vitro was assessed by counts of nucleated red cells and 3H-thymidine incorporation into erythroid precursors. Human urinary erythropoietin was found to stimulate erythropoiesis in cultures from the polycythaemia patients as well as normals. The erythropoietin effect was blocked by a rabbit anti-erythropoietin antibody. These results suggest that some erythroid precursor cells maintain an intact erythropoietin response mechanism in polycythaemia vera. They also support clinical studies of this disorder indicating that some regulation by erythropoietin may occur in vivo.