期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1982
卷号：79
期号：21
页码：6579-6583
DOI：10.1073/pnas.79.21.6579
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：An erythropoietic activity that exerts a profound effect on fetal Hb synthesis is present in fetal sheep sera and it attains a peak concentration at the end of the second to the middle of the third trimester of fetal life. The activity consistently inhibits the increased synthesis of fetal Hb in cultures of burst-forming units (BFUes) from normal adults. In cultures of BFUes from homozygous beta+-thalassemias the activity produces a striking decline in gamma chain synthesis, a decline in G gamma/A gamma chain synthesis ratio, and an increase in delta/gamma and alpha/non-alpha ratios--i.e., findings suggesting a genuine gamma-to-beta switch. The activity accelerates Hb F-to-Hb A switching in neonatal BFUe cultures but it has no effect on fetal Hb synthesis in cultures of BFUe obtained from human fetuses. These findings provide direct evidence that (a) humoral factors play a role in the regulation of the switch from fetal to adult Hb formation, and (b) progenitor cells from various stages of ontogeny respond differently to these factors. The results are compatible with the hypothesis that Hb switching during development is mediated through a change in a developmental program which controls the responsiveness of progenitor cells to "switching" activities in their environment.
