Applicability of four new antibodies for the detection of fetal nucleated cells out of maternal blood by FISH analysis

The availability of fetal cells from the maternal peripheral blood opens up the possibility for a noninvasive prenatal diagnosis. Until now this prosp ect has been hampered by the fact that there are no highly specific antibod ies to fetal cells. In the present study, four as yet untested monoclonal a ntibodies - 2G5, 3F9, EPO-R and Flk1 were analyzed in view of their effecti veness to stain fetal nucleated cells, Therefore, 20 mi of peripheral blood from 40 women carrying a male fetus were collected in the 16th to 28th wee ks of pregnancy. Mononucleated cells, enriched by density gradient, were st ained with one of the four antibodies and isolated with magnetic cell sorti ng, Subsequently, fluorescence in situ hybridization with chromosome X and Y centromere probes was performed which allowed us to analyze the maternal or fetal origin of the enriched cells. For evaluation, 500 nuclei per case were examined. The antibody 3F9 detected 0.2 cells on average (n = 5), 2G5 1.2 (n = 11), EPO-R 1.6 (n = 10) and Flk1 1.8 cells (n = 8) with fetal spec ific Y-positive hybridization signals. The antibody against CD71 (n = 6) us ed as control gave no Y-specific signals. Considering these results, the te sted antibodies, especially Flk1, appear to be more successful in detecting fetal cells than the commonly used CD71 antibody. Copyright (C) 2001 S. Ka rger AG, Basel.