Hemoglobin switching in sheep: characteristics of BFU-E-derived colonies
from fetal liver
JE Barker
Two types of erythroid colonies were generated in vitro from sheep fetal
liver cells. The first type consisted of single colonies of 8-256 cells
that were well hemoglobinized by 4 days; these are thought to originate
from CFU-E. The second type consisted of macroscopic colonies composed of
several subcolonies that matured between days 3 and 8 in vitro. At
maturity, each contained 256 to > 1000 cells that formed a discrete
macroscopic cluster. The macroscopic colonies, not previously described in
sheep, are thought to be derived from BFU-E. The characteristics of sheep
BFU-E were defined and the production of fetal hemoglobin (HbF, alpha 1,
gamma 2) and HbC (alpha 2 beta 2) was compared in colonies derived from
CFU-E or BFU-E. Bursts developed at erythropoietin (epo) concentrations as
low as 0.1 U/ml, although the number observed increased with epo
concentration up to 10 U/ml. The number of bursts observed was
approximately proportional to the number of cells plated. As shown by
thymidine suicide, approximately 50% of both the BFU e and CFU-E were in
S-phase when obtained from the fetus. BFU-E were smaller and partially
separable from CFU-E after sedimentation at unit gravity. The beta c/gamma
synthetic ratio in colonies derived from BFU-E was greater than in
CFU-E-derived colonies. These data suggest that the capacity for generation
of erythroblasts making HbC is greater in the earlier or more primitive
erythroid stem cells in fetal liver.
Volume 56,
Issue 3,
pp. 495-500,
09/01/1980
Copyright © 1980 by The American Society of Hematology
