Cord blood LAK cells can kill YAC-1 target cells by apoptosis. Cord blood mononuclear cells were cultured in IL-2 (500 U/mL) at 37°C. After 3 days, the cells were washed and 5 × 10⁶ cells were incubated with 5 × 10⁵ YAC-1 target cells that had been prelabeled with ¹²⁵I-UdR. After 4 hours, DNA was extracted from the cell mixture, electrophoresed, and autoradiographed. The left-hand lane shows DNA extracted from YAC-1 cells in isolation. The right-hand lane shows YAC-1 DNA extracted from the cell mixture preparation. The DNA ladder is indicative of apoptosis. This figure is representative of three experiments.