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.