The host γδ T cells but not αβ T cells amplify the severity of GVHD. (A,B) αβ^-/- mice (▪, n = 11), γδ^-/- mice (▴, n = 13), or wt mice (•, n = 10) received transplants from allogeneic BALB/c or syngeneic B6 donors (○, n = 10) as in Figure 1 and were evaluated for survival (A) and clinical GVHD score (B). Data from 2 similar experiments are combined. ▴ vs ▪, ^**P < .01, ▪ vs •, P = .26 by Wilcoxon rank test. ▴ vs ▪, ^*P < .05, ▪ vs •, P = .43 by Mann-Whitney U test from weeks 1 to 5. Error bars represent standard error. (C,D) γδ⁺ splenocytes (, n = 12), αβ⁺ splenocytes (, n = 8) or media (▴ and solid line, n = 8) were injected into γδ^-/- (60 × 10⁶ cells/mouse). Wt B6 mice (• and solid line, n = 12) were injected with media alone. Twenty-four hours later, all mice received transplants from allogeneic BALB/c donors as in Figure 1 and were evaluated for survival (C) and clinical GVHD score (D). Data from 2 similar experiments are combined. vs , ^**P < .01 by Wilcoxon rank test. vs , weeks 3 to 5, ^*P < .001 by Mann-Whitney U test. Error bars represent standard error.