Male fetal progenitor cells persist in maternal blood for as long as 27 years postpartum.

Rare nucleated fetal cells circulate within maternal blood. Noninvasive prenatal diagnosis by isolation and genetic analysis of these cells is currently being undertaken. We sought to determine if genetic evidence existed for persistent circulation of fetal cells from prior pregnancies. Venous blood samples were obtained from 32 pregnant women and 8 nonpregnant women who had given birth to males 6 months to 27 years earlier. Mononuclear cells were sorted by flow cytometry using antibodies to CD antigens 3, 4, 5, 19, 23, 34, and 38. DNA within sorted cells, amplified by PCR for Y chromosome sequences, was considered predictive of a male fetus or evidence of persistent male fetal cells. In the 32 pregnancies, male DNA was detected in 13 of 19 women carrying a male fetus. In 4 of 13 pregnancies with female fetuses, male DNA was also detected. All of the 4 women had prior pregnancies; 2 of the 4 had prior males and the other 2 had terminations of pregnancy. In 6 of the 8 nonpregnant women, male DNA was detected in CD34+CD38+ cells, even in a woman who had her last son 27 years prior to blood sampling. Our data demonstrate the continued maternal circulation of fetal CD34+ or CD34+CD38+ cells from a prior pregnancy. The prolonged persistence of fetal progenitor cells may represent a human analogue of the microchimerism described in the mouse and may have significance in development of tolerance of the fetus. Pregnancy may thus establish a long-term, low-grade chimeric state in the human female.

Transferrin receptor (CD71) expression on circulating mononuclear cells during pregnancy.

OBJECTIVE: We studied transferrin receptor (CD71) expression in peripheral blood mononuclear cells from healthy pregnant women, to determine if a relationship existed between gestational age and circulating CD71+ mononuclear cells. STUDY DESIGN: Cell suspensions were prepared from venous blood from 139 pregnant women (7 to 26 weeks of gestation), incubated with monoclonal anti-CD71 antibody, and analyzed by flow cytometry. RESULTS: When only the first sample from each woman was analyzed, extensive biologic variation between women was shown. An apparent biphasic increase in the percentage of CD71+ cells with advancing gestation was suggested. A subgroup of 13 women studied on multiple occasions demonstrated linear increases in CD71+ cells as pregnancy progressed. CONCLUSIONS: Pregnant women, when compared with each other, may have differences in the baseline number of circulating CD71+ cells. The increases seen in individuals studied repeatedly are likely to reflect maternal hematopoiesis and current fetomaternal transfusion.

Erythroid-specific antibodies enhance detection of fetal nucleated erythrocytes in maternal blood.

Fetal nucleated erythrocytes (NRBC) in maternal blood are a non-invasive source of fetal DNA for prenatal genetic screening. We compared the effectiveness of three monoclonal antibodies for the separation of fetal cells from maternal blood by flow sorting. Mononuclear blood cells from 49 healthy pregnant women were incubated with antibody to CD 71, CD 36, and/or glycophorin A (GPA), employed singly or in combination with each other. These monoclonal antibodies recognize surface antigens on haematopoietic precursor cells. Successful isolation of fetal cells was defined as detection of Y chromosomal sequences in maternal blood from women carrying male fetuses, with absence of Y sequences when female fetuses were carried. Thus, gender prediction accuracy was used as a measure of fetal cell separation. Using anti-CD 71 to isolate fetal cells, gender prediction was 57 per cent correct; with anti-CD 36, it was 88 per cent correct. Anti-GPA, an erythrocyte-specific antigen, used alone or in combination with anti-CD 71 or 36, improved gender prediction to 100 per cent. We conclude that antibody to GPA improves the retrieval of fetal NRBC from maternal blood, permitting genetic analysis by the polymerase chain reaction.

Detection of fetal cells with 47,XY,+21 karyotype in maternal peripheral blood.

Fetal cells were isolated from the peripheral blood of a pregnant woman at 19 weeks of gestation whose fetus had Down syndrome. An amniocentesis had been performed 2 weeks earlier because of abnormalities detected on an antenatal sonogram. Fetal cells were separated by fluorescence-activated cell sorting using monoclonal antibody to the transferrin receptor (TfR). Fluorescence in situ hybridization studies with probes for chromosomes Y and 21 revealed a small number of 47,XY,+21 cells in the TfR+ sorted fraction. Although preliminary, the results of this study suggest the possibility that one day, fetal chromosome aneuploidy will be routinely diagnosed from maternal venous blood samples.