Studies on the isolation and identification of fetal nucleated red blood cells in the circulation of pregnant women before and after chorion villus sampling.
OBJECTIVE
To investigate the feasibility of various molecular forms of hemoglobin as markers for fetal nucleated red blood cells (NRBCs).


METHODS
The presence of epsilon and gamma globin positive NRBCs was investigated in pure fetal blood and in blood from pregnant women before and after chorion biopsy. Maternal samples were enriched for NRBCs by various conventional methods, including limited enrichment by only positive CD71 selection or single density gradient. We searched for fetal cells on slides by automated scanning. Fetal cells were defined by (1) the presence of epsilon or gamma globin and (2) simultaneously by the presence of a Y chromosome signal.


RESULTS
18 of 25 gamma globin positive cells identified in blood samples after chorion biopsy were chromosome Y signal positive, and 1 cell had two X chromosome signals. 263 of 339 epsilon globin positive cells identified in blood samples after chorion biopsy were hybridized with X and Y chromosome probes. None had two X signals, and 249 were Y positive. In blood samples before chorion biopsy, only 1 epsilon globin positive fetal NRBC and no epsilon globin positive maternal NRBCs were found.


CONCLUSIONS
Epsilon globin may be specific for fetal NRBCs. Only 1 epsilon globin positive fetal cell was identified in 1 of 12 blood samples before chorion biopsy, representing a total of 182 ml of maternal blood. This suggests that most fetal cells found in maternal blood by fluorescence in situ hybridization methods may not be NRBCs.
Christensen
B
B
Research Unit for Prenatal Diagnosis, The Juliane Marie Center, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark. b.christensen@rh.dk
Kølvraa
S
S
Lykke-Hansen
L
L
Lörch
T
T
Gohel
D
D
Smidt-Jensen
S
S
Bang
J
J
Philip
J
J
D000918:Antibody Specificity; D015415:Biomarkers; D002469:Cell Separation; D015193:Chorionic Villi Sampling; D002869:Chromosome Aberrations; D004900:Erythroblasts / Q000166:cytology*; D005260:Female; D005315:Fetal Diseases / Q000175:diagnosis*; D005319:Fetal Hemoglobin / Q000276:immunology; D006801:Humans; D008431:Maternal-Fetal Exchange; D011247:Pregnancy
D015415:Biomarkers; D005319:Fetal Hemoglobin