Diagnosing and preventing inherited disease: Nucleated erythrocytes in maternal blood: quantity and quality of fetal cells in enriched populations

Abstract

The discovery of nucleated erythrocytes in maternal circulation provides a potential source for non-invasive prenatal diagnosis. We have evaluated the use of a three-stage procedure to determine the number of cells that are of fetal rather than maternal origin. First, monoclonal antibodies specific for CD45 and CD14 were used in conjunction with a magnetic (MACS) column to deplete unwanted leukocytes from maternal blood. This was followed by a positive MACS enrichment for nucleated erythrocytes, using an anti-CD71 (transferrin receptor) monoclonal antibody. To discriminate between fetal nucleated erythrocytes and those of maternal origin, enriched fractions were simultaneously stained with an anti-fetal haemoglobin (HbF) antibody and hybridized with probes specific for X and Y chromosomes. Samples were then subjected to blind analysis along with negative control samples from non-pregnant volunteers. Using this dual analysis, we were able to determine that less than one nucleated erythrocyte per ml of maternal blood was of fetal origin. Small numbers of these fetal cells were found in 87.5% of pregnancies, ranging from 6 to 35 weeks gestational age. Comparison of HbF and X/Y probe data also suggests that the fetal cells are less suitable for fluorescence in-situ hybridization (FISH) analysis than similar preparations from other sources.

Overview and recent developments in cell‐based noninvasive prenatal testing

“…Hence, considerable efforts were made from the 1980s to early 2000s to find adequate, general markers for specific fnRBC selection. The surface marker CD71 (transferrin receptor) combined with CD36 and/or glycophorin A (GPA) are the most widely used targets, 48,[58][59][60] and Bianchi and colleagues showed that adding anti-GPA antibodies to anti-CD71 or anti-CD36 substantially improves fnRBC selection and accuracy of fetal sex prediction. 61,62 Choolani et al confirmed that primitive erythroblasts were the predominant cell type up to 12 weeks gestation, declining rapidly thereafter.…”