Heterogeneity of F cells in β-thalassemia
Article first published online: 27 JUN 2012
© 2012 American Association of Blood Banks
Volume 53, Issue 3, pages 499–504, March 2013
How to Cite
Prus, E. and Fibach, E. (2013), Heterogeneity of F cells in β-thalassemia. Transfusion, 53: 499–504. doi: 10.1111/j.1537-2995.2012.03769.x
- Issue published online: 8 MAR 2013
- Article first published online: 27 JUN 2012
- Received for publication March 7, 2012; revision received May 16, 2012, and accepted May 18, 2012.
BACKGROUND: Fetal hemoglobin (HbF), which is largely replaced after birth by the adult Hb, is concentrated in a few “F cells.” Their number significantly increases in certain physiologic and clinical situations, including in β-thalassemia (β-thal). Their quantification is used to detect fetal–maternal hemorrhage (FMH), where fetal cells enter the maternal circulation. We were confronted with a pregnant woman with β-thal who was suspected to have FMH. To establish the usefulness of a flow cytometric procedure to differentiate between fetal cells and the maternal F cells, we screened adult β-thal patients.
STUDY DESIGN AND METHODS: Blood samples were simultaneously stained with fluorescent antibodies to HbF and to carbonic anhydrase (CA) isotype II, which is specific to adult red blood cells (RBCs).
RESULTS: A heterogeneous distribution of RBCs with respect to HbF and CA expression was observed: adult non-F cells (CA+HbF–) and F cells (CA+HbF+/HbF++) as well as F cells with characteristics of fetal cells (CA–HbF++).
CONCLUSIONS: The presence of CA–HbF++ RBCs in nonpregnant women, and even men, with thal indicates that the CA/HbF method is inappropriate for detection of FMH. The coexistence of F cells carrying fetal or adult markers suggests that they originate from two types of stem cell, adult and fetal, lineages. Normally, the fetal lineage is insignificant, but in β-thal, as HbF-containing RBCs have a selective advantage, the “fetal” lineage gains significance.