The absence of DNAM-1 on donor cells attenuates acute GVHD. (A-D) 5 × 10⁶ BM and 0.5 × 10⁶ CD3⁺ T cells from B6.WT or B6.DNAM-1^−/− donor mice were transplanted into lethally irradiated C3H recipients. Survival (A) and clinical score (B) are shown. P < .0001, B6.DNAM-1^−/− vs B6.WT. *P < .05, B6.DNAM-1^−/− vs B6.WT. Data shown are combined from 2 replicate experiments (n = 15 per T-cell–replete group and n = 7 in T-cell–depleted [TCD] control). (C,D) Tissues from skin, liver, and small intestine of C3-recipient mice were taken 20 days after transplantation. (C) Semiquantitative histopathology and (D) representative images (magnification ×250) from small intestine. Scale bars represent 100 μm. (n = 8 to 9 in T-cell–replete groups and n = 3 in TCD control). (E,F) 5 × 10⁶ BM and (E) 5 × 10⁶ or (F) 1 × 10⁶ CD3⁺ T cells from B6.WT or B6.DNAM-1^−/− donor mice was transplanted into lethally irradiated BALB/B recipients. (E) P = .0026, B6.DNAM-1^−/− vs B6.WT. Survival data shown are combined from 2 replicate experiments (n = 15 per T-cell–replete group and n = 3 in TCD control). (F) ***P = .0002; **P < .008; *P < .02; B6.DNAM-1^−/− vs B6.WT. Survival data shown are combined from 2 replicate experiments (n = 14 per T-cell–replete group and n = 5 in TCD control).