Identification of fetal nucleated red cells in co-cultures from fetal and adult peripheral blood: Differential effects of serum on fetal and adult erythropoiesis

Seeking to optimize a novel method of isolating rare fetal erythroid cells in cultures from maternal blood, we have explored the effects of serum supp lement on fetal and adult erythropoiesis. We used flow cytometry and sortin g after labelling with antibodies to fetal haemoglobin (HbF) and adult haem oglobin (HbA). In adult blood-derived cultures, most nucleated red cells ac cumulated either only adult haemoglobin (F - A+) or a combination of fetal and adult haemoglobin (F+A+). Only a few were F+A-. Serum affected the prop ortions of adult cells expressing fetal haemoglobin (both F+A- and F+A+), w hich were minimized, but not eliminated altogether, with the use of charcoa l-treated sera at low concentrations. In contrast, the expansion of fetal r ed cells, which made only fetal haemoglobin (F+A-) during at least one week of culture, was strongly increased with the use of charcoal treated sera, due to the removal of a charcoal-absorbable inhibitor. In co-cultures of fe tal and adult erythroid cells, fetal cells could be enriched in the order o f 200-fold by flow sorting with the F+A- criterion. However, since adult FA- cells could not be suppressed completely, the purity of sorted fetal cel ls still depended on the relative numbers of fetal and maternal erythroid c lonogenic cells in the blood sample. Thus, we demonstrate a method by which fetal nucleated red cells potentially present in maternal blood cultures c an be identified and isolated from the vast majority of maternal erythroid cells, based on their correlated contents of fetal and adult haemoglobin. C opyright (C) 1999 John Wiley & Sons, Ltd.