Erythropoiesis. Regulatory Mechanisms and Developmental Aspects

This volume contains the proceedings of a conference on erythropoiesis held at Tel Aviv University from July 27-29, 1970. Twenty-seven papers are listed under six headings: "Fetal and Neonatal Erythropoiesis," "Assay of Erythropoietin," "Androgens and Erythropoiesis," "Mechanism of Action of Erythropoietin," "Regulation of Erythropoiesis," and "Production of Erythropoietin: Renal and Extrarenal Sources and Inhibitors of Erythropoietin." The discussions following the presentations are also recorded, a useful addition. Much has been learned about erythropoietin and the editor expects a new surge of progress with the imminent availability of in vitro assays. Herein described are a hemagglutination-inhibition assay and a radioimmunoassay for erythropoietin thought by those who described them to be sensitive and specific. At the time of the conference neither assay had been tried in large groups of human subjects. It is clear that these were still relatively preliminary communications since the other papers in this volume relied on the rodent bioassay systems. The application of erythropoietin assays to the workup of clinical problems may be possible with the development of the newer methods. For example, we may be able to distinguish tumor-induced erythrocytosis from polycythemia vera by serum urinary ESF levels. Another portion of the conference recorded in this volume that is of immediate clinical significance contains papers on the relationship between androgen and erythropoiesis. It is certainly puzzling that androgens benefit persons with aplastic anemia, whose erythropoietin output is usually increased, when the principal effect of androgens seems to be to further increase erythropoietin. Clearly the relationship between androgens, erythropoiesis, and hematological improvement in an individual with aplastic anemia is not a simple one. That the effect of androgens on erythropoiesis is indirect is supported by previous work and by several papers presented at this conference. It has been established that testosterone has little effect on increasing erythroid marrow precursors in the perfused hind limb of a dog. A contribution to this volume showed that testosterone succinate had no effect on iron incorporation in rabbit bone marrow cells in culture. Another paper reviewed evidence that testosterone acts through erythropoietin-the effect of testosterone and other hormones (ACTH, thyroid) can be prevented by erythropoietin antibodies. On the positive side, kidneys isolated from previously hypoxic dogs and perfused with blood containing testosterone produced high levels of erythropoietin. Another author showed that several different types of testosterone had positive erythropoietic effects, that there was a correlation between renotropic and