Cord blood and BM mononuclear cells were isolated and cultured in IL-2 (500 U/mL). After 3 days, the cells were washed and their cytotoxicity against Daudi and YAC-1 cells was measured using the⁵¹Cr and ¹²⁵I-UdR release assays, respectively. Figures show the % kill ± 1 SD. A constant E:T of 25:1 was used. The average spons/max ratios were 14.8% for the Daudi cell experiments and 10.0% for the YAC-1 cell experiments. The Mann Whitney statistical test was used to compare data.