DLI activates functional DN T cells in nontransgenic mice.

(A) A group of (B6 × dm2)_F1 mice were given DLI and transplants. At 1 week after transplantation, spleen cells were harvested from 4 mice and DN T cells were purified. Activated anti-L^d (dark bars) or anti-H-2^s (light bars) CD8⁺ T cells were used as targets at the effector-to-target ratios indicated. Shown is the mean percentage of specific killing ± SD for 3 replicates. (B,C) A group of B6 × dm2_F1 mice were given DLI (B) or left untreated (C) and then given transplants. At 1 week after transplantation, graft-infiltrating cells were harvested and stained by using anti-CD3, anti-CD4, and anti-CD8 mAbs. Data shown are gated on CD3⁺ T cells and represent pooled results from 4 mice. (D) Graft-infiltrating T cells were purified from the L^d+ graft of DLI-treated (B6 × dm2)_F1 mice 1 week after skin grafting. DN T cells were purified and used as putative suppressor cells (5000 cells/well). Splenocytes from naive (B6 × dm2)_F1 mice were used as responder cells and were stimulated with either (B6 × BALB/c)_F1 (L^d+) or SJL (H-2^s) irradiated splenocytes as indicated. Shown is the percentage of inhibition of proliferation of CD8⁺ responder cells (pooled results from 4 mice).