ETCs primed with B6-DCs_C1498 in vitro mediate strong GVL effects in leukemia-bearing MC and FC recipients after delayed transfer. Hematopoietic chimeras were established with a mixture of 15 × 10⁶ TCD B10.A BM plus 5 × 10⁶ TCD B6 BM for MCs or with 15 × 10⁶ TCD B10.A BM alone for FCs. The recipients were injected with 0.6 × 10⁶ C1498 cells intravenously on day 55. On day 56, the recipients were treated with 40 × 10⁶ effector cells. Survival was monitored in MC and FC recipients for 100 days after treatment. As effectors either (A) ETCs:R-DCs_pulsed (-♦-, n = 9-MC, 18-FC), (B) ETCs:D-DCs_pulsed (-♦-, n = 9), or (C) ETCs:R-DCs_nonpulsed (-◇-, n = 9) were given. Naive DLI (-■-) and PBS (-▴-) were given as controls. P greater than or equal to .05 was considered not significant (NS).