IL-21 signaling is not required for GVL against hematopoietic malignancy. (A) Lethally irradiated BALB/c mice were transplanted with either B6 BM-TCD alone or with A20 tumor cells (2.5-5 × 10⁵) with or without WT versus IL-21R KO T cells (0.5-1 × 10⁶). Recipients were followed for mortality, and curves represent combined data from 4 independent experiments (n = 19-20 for non–T-cell groups, n = 39 for T-cell groups). (B) Lethally irradiated B6 × DBA/2 F1 mice were transplanted with either B6 BM-TCD alone or with P815 tumor cells (1 × 10³) with or without WT versus IL-21R KO T cells (1 × 10⁶). Recipients were followed for mortality, and curves represent combined data from 2 independent experiments (n = 10 for non–T-cell groups, n = 20 for T-cell groups). ***P < .001 for WT versus KO T cells.