Apoptosis of rat uterine NK cells in vitro

The viability of rat uterine natural killer (NK) cells in vitro was examined. Uterine NK cells were obtained from rats on days 10 and 16 of pregnancy and they were cultured in RPMI 1640 medium supplemented with 10% v/v fetal calf serum in the presence or absence of human recombinant IL-2 or cycloheximide for 24, 48, 72 and 96 h. In both preparations of cells collected on days 10 and 16 of pregnancy, about 60% of the cells died during the first 48 h of culture regardless of the presence of IL-2. Gel electrophoresis of genomic DNA showed ladder fragmentation with 180 to 200-bp fragments, indicating that the cell death was due to apoptosis. Apoptosis of uterine NK cells in vitro was promoted, not prevented, by cycloheximide. The remaining uterine NK cells (40%) were maintained alive under these culture conditions for, at least, 96 h. Therefore, rat uterine NK cells undergo apoptosis and are consist of subpopulations with referring viabilities in vitro.