Submitted September 13, 2005
Accepted March 13, 2006
The Effect of Fetal Hemoglobin on the Survival
Characteristics of Sickle Cells
Robert S Franco*, Zahida Yasin, Mary B Palascak, Peter Ciraolo, Clinton H Joiner, and Donald L. Rucknagel
Division of Hematology/Oncology,Cincinnati Comprehensive Sickle Cell Center,University of Cincinnati
Division of Pediatric Hematology/Oncology, University of Cincinnati
Division of Hematology/Oncology, Division of Pediatric Hematology/Oncology, University of Cincinnati
* Corresponding author; email: robert.franco{at}uc.edu.
The determinants of sickle red blood cell (RBC) lifespan
have not been well-defined, but may include both
intrinsic factors (e.g., the tendency to sickle) and
extrinsic factors (e.g., the capacity of the
reticuloendothelial system to remove defective RBC).
HbF is heterogeneously distributed among sickle RBC; F-
cells contain 20-25% HbF, whereas the remainder have no
detectable HbF (nonF-cells). Autologous sickle RBC were
labeled with biotin and reinfused to determine overall
survival, nonF- and F-cell survival, and time-dependent
changes in HbF content (%HbF) for the surviving F-
cells. A total of ten patients were enrolled, including
two who were studied before and after the percentage of
F-cells was increased by treatment with hydroxyurea. As
expected, F-cells survived longer in all subjects. NonF-
cell survival correlated inversely with the percentage
of F-cells, with the time for 30% cell survival ranging
from 6 days in patients with > 88% F-cells to 16 days in
patients with < 16% F-cells. As the biotin-labeled RBC
aged in the circulation, the HbF content of the
surviving F-cell population increased by 0.28 ±; 0.21
%/day, indicating that within the F-cell population
those with higher HbF content survived longer.
