A20-specific T-cell memory following immunization with unloaded DCs. (A) Mice that had rejected a primary A20 challenge after DC injection were rechallenged with a lethal dose of A20 lymphoma 150 days later (). Other groups were additionally treated with the NK cell–depleting mAb TMβ1 (▪) or the anti–T-cell mAb MmT1 (▴) during the effector phase. × indicates tumor control. (B) CD8⁺ T cells were isolated from spleens of naive or immune mice 4 days after DC injection. IFN-γ secretion was determined in the presence of irradiated A20 cells. Results were corrected for IFN-γ secretion in the absence of A20. (C) T cells were further stimulated for 9 days with DCs, and reactivity was determined against A20, MPC11, CT26, and bone marrow–derived DCs that were or were not treated with LPS (mDC and iDC, respectively). IFN-γ secretion in medium alone was subtracted. Error bars in panels B and C indicate standard deviation. (D) T cells were isolated from DC-immunized (▴) or untreated (▪) mice, stimulated in vitro, and adoptively transferred to naive mice together with a lethal A20 challenge. × indicates tumor control. T cells from mice that were only injected with A20 had no effect.