Enrichment of fetal cells from maternal blood by magnetic activated cell sorting (MACS) with fetal cell specific antibodies: one-step versus two-step MACS.

Abstract

We report here the results of fetal cell enrichment from maternal blood in 58 pregnant women by the use of magnetic activated cell sorting (MACS) with erythroblast-specific and/or maternal cell specific antibodies. Two approaches were compared; one-step MACS to enrich CD71+ (a membrane-bound marker) or GPA+ (another marker, glycophorin A) fetal cells versus two-step MACS to deplete CD14+ maternal cells and subsequently to enrich fetal (CD71+ or GPA+) cells. The existence of fetal cells was ensured by both FISH with Y-specific probes and karyotyping of respective amniotic and/or chorionic vullus cells, the results being applied for comparison of detection rate for XY fetuses between the two MACS procedures. In 24 (38.8%) of the 58 blood samples examined, Y-positive cells were observed by FISH, whereas there were 38 true XY fetuses later confirmed by karyotyping, including two cases of 47,XY,+21. On the other hand, in Y-negative cells by FISH, there were two cases of 47,XX,+18. The average number of cells sorted did not differ among one-step MACS procedures with anti-CD14, anti-CD71 and anti-GPA antibodies. With the latter, 12 (75%) of 16 Y-positive fetuses were detected, while only one (20%) of 5 Y-positive fetuses was detected by two-step MACS with anti-CD14/anti-GPA antibodies. The detection rate significantly varied (p = 0.0024) between the two procedures, although the numbers of cases examined were small. There was no statistical difference (p > 0.05) between one-step and two-step MACS with other combinations of antibodies. These findings indicate that one-step MACS using the anti-GPA antibody is more effective than two step MACS for enrichment of fetal cells from maternal blood.