Thymic-dependent GVHD after allogeneic TCD-BMT from MHC class II–deficient donors. C3H mice were irradiated and underwent transplantation with TCD-BM from either control WT or H2-Ab1^−/− B6 donors. Weight changes as the mean ± SE (A) and survivals (B) after BMT are shown. Data from 3 similar experiments are combined. ○, [WT → C3H], n = 22; •, [H2-Ab1^−/− → C3H], n = 27. (C) Lethally irradiated BALB/c mice underwent transplantation with TCD-BM from either control WT or H2-Ab1^−/− B6 donors. The survivals after BMT are shown. □, [WT → BALB/c], n = 6; ▪, [H2-Ab1^−/− → BALB/c], n = 7. (D-E) C3H mice were thymectomized (Tx) and underwent transplantation with TCD-BM from H2-Ab1^−/− B6 donors following 13 Gy TBI (▵, n = 4). Nonthymectomized C3H mice also underwent transplantation with TCD-BM from WT (○, n = 4) and H2-Ab1^−/− (•, n = 6) B6 donors following TBI. Survivals (D) and weight changes as the mean ± SE (E) are shown. *P < .05, **P < .001.