DEMONSTRATION OF SPONTANEOUSLY DIVIDING MALE FETAL CELLS IN MATERNAL BLOOD BY NEGATIVE MAGNETIC CELL SORTING AND FISH

We investigated a case of massive fete-maternal bleeding by using nega tive magnetic cell sorting (MACS) and fluorescent in situ hybridizatio n (FISH). A 37-year-old pregnant woman had an uncomplicated amniocente sis for advanced maternal age at 16 weeks' gestation. The fetal karyot ype was 46,XY. At 19 weeks' gestation, she had a minor car accident an d slight vaginal bleeding. A subsequent Kleihauer-Betke test showed a 140 ml fete-maternal haemorrhage. Serial sonographic examinations indi cated a normal fetus and placenta. We performed FISH analysis on mater nal peripheral blood at 25 weeks. Anti-CD45 and MACS were used to depl ete maternal leucocytes, enriching the proportion of fetal nucleated e rythrocytes present. The isolated cells were analysed by using dual-co lour FISH with X and Y specific probes. Approximately 65 800 nucleated cells were obtained after MACS depletion. A total of 234 cells were a nalysed by FISH. The results revealed that 70 of the nucleated cells ( 30 per cent) were male with one X and one Y signal. Among these cells, six male metaphases were observed in spontaneously dividing cells.