Comparison of anti-gamma hemoglobin antibody and CD71 antibodies in isolation of fetal nucleated erythrocytes from maternal blood.

Objective: In an attempt to further maximize the potential of genetic analysis from fetal cells isolation, fetal nucleated red blood cell (FNRBC) recovery with direct anti-gamma hemoglobin staining after density gradient and depletion was compared with three different whole blood magnetic separations (1-step and 2-step ferrofluid, 2-step Dynal beads). Methods: In model systems such as quantitatively defined spikes of fetal into adult blood, as well as blood samples after surgical termination procedures, fetal cell yield and purity through the results of fluorescence in situ hybridization (FISH), quantitative real time polymerase chain reaction (PCR), and fluorescence-activated cell sorting (FACS) were calculated. Results: The yield of total number of cells with a XY signal after FISH was the highest on direct anti-gamma hemoglobin staining. After normalizing the results of each experiment to the corresponding result from anti-gamma hemoglobin staining (1), ratio is 0.42 in 1-step ferrofluid, 0.33 in 2-step ferrofluid, and 0.76 in 2-step dynal beads. The fetal cell purity is clearly better in direct anti-gamma hemoglobin staining than those of the magnetic separations from whole blood. The median ratio is 56.3% in anti-gamma hemoglobin staining, 7.7% in 1-step ferrofluid, 6.5% in 2-step ferrofluid, and 31.4% in 2-step dynal beads. Conclusion: This study shows that the direct anti-gamma staining is the best fetal cell recovery system and it is very useful to isolate fetal nucleated red blood cells as a non-invasive genetic source.