Purging of C1498 leukemia with allogeneic B10.D2 ALAK cells ex vivo results in increased inhibition of tumor growth and survival of mice. BMCs (3.6 × 10⁷) from B6 mice and C1498 leukemia cells (3.6 × 10⁵) were cultured with or without B10 or B10.D2 ALAK cells (3.6 × 10⁷) in 10% IMDM containing 5000 IU/mL rhIL-2 in T-25 flasks for 24 hours. (A) A fraction of the cocultured cells was plated back in 96-well, flat-bottomed microtiter plates at 2 × 10³ C1498 cells per well based on the cell numbers at the initiation of the coculture in triplicate to assess proliferation using [³H]-thymidine, as described in “Materials and methods.” The [³H]-thymidine incorporation of BMC + C1498 control was 2.1 × 10⁴ cpm at day 5. Results from 1 of 2 representative independent experiments are shown, and the statistical difference between cell growths at various days was determined using the unpaired t test with Welch correction. (B) Cocultured cells were injected into irradiated (8 Gy) B6 recipient mice (10 mice per group per experiment) at 3 × 10⁴ C1498 cells per mouse (intravenously) based on the cell number at the initiation of coculture, and mice were monitored for survival. Pooled data from 2 independent experiments are shown, and the statistical difference between the groups was determined using the log-rank test.