Distribution of fetal and embryonic hemoglobins in fetal erythroblasts enriched from maternal blood

Background and Objectives. To determine the distribution of embryonic and f etal hemoglobin chains in fetal erythroblasts isolated from maternal blood in the first trimester of pregnancy and establish the feasibility of using these chains as markers for fetal cell identification, Design and Methods, Maternal blood was obtained from 187 singleton pregnanc ies at 11-14 weeks of gestation immediately before fetal karyotyping by cho rionic villus sampling, In all cases included in this study the fetal karyo type was normal, Fetal erythroblasts were isolated using triple density gra dient separation and anti-CD71 magnetic cell sorting techniques, The enrich ed erythroblasts were stained with Kleihauer-Giemsa and with fluorescent an tibodies for the zeta (zeta), epsilon (epsilon) and gamma (gamma) globin ch ains. The percentage of fetal cells positive for each stain was calculated, Fluorescent in situ hybridization (FISH) for X and Y chromosomes was also performed. Comparison was made with the percentage of cells with positive Y -signal FISH in pregnancies with male fetuses. Results. The percentage of fetal erythroblasts stained positive was 37% for the zeta and 95% for both E and gamma globin chains, as well as the Kleiha uer-Giemsa staining, There was a significant association between the Kleiha uer-Giemsa stained cells and those stained with epsilon and gamma globin ch ains. There was also an association between cells with Y-signals and those stained with epsilon and gamma globin chains. Interpretation and Conclusions. Embryonic hemoglobin chains can be detected in the enriched fetal erythroblasts, with higher percentages of the epsilo n rather than the zeta globin chains, These chains are therefore potentiall y unique markers to be used in the identification of cells of fetal origin from maternal blood for prenatal diagnosis of genetic and chromosomal abnor malities. (C) 2001, Ferrata Storti Foundation.