Studies on the isolation and identification of fetal nucleated red blood cells in the circulation of pregnant XXXX before and after chorion villus sampling.

@entity1 @entity6618 @entity8282
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 @entity1 before and after chorion biopsy. Maternal samples were enriched for NRBCs by various conventional methods, including limited enrichment by only positive @entity8282 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 @entity6618 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 @entity6618 positive fetal NRBC and no @entity6618 positive maternal NRBCs were found. CONCLUSIONS: @entity6618 may be specific for fetal NRBCs. Only 1 @entity6618 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.
