Mitosis of maternal lymphocytes in the presence of fetal cells: possible implication in prenatal diagnosis from fetal blood samples.

The suppression of proliferation of maternal lymphocytes by the lymphocytes of their own male newborns have been tested in a PHA-induced two-way stimulation system. The mixed lymphocyte cultures of 6 out of 12 such mothers/son pairs had 23--50% metaphases with 46,XX karyotype. In 2 more cases 10% maternal metaphases have been observed. Hence, it appears that fetal lymphocytes are unable to suppress the proliferation of maternal cells completely.