Reduction of GVHD mortality and morbidity in BMT (B6 → B6D2F1) after reduced conditioning TBI. Results represent a combination of two experiments in which allogeneic arms are represented by solid and syngeneic arms are represented by open symbols: 1,300 cGy TBI (•), n = 15; 900 cGy TBI (▪), n = 15; 1,300 cGy TBI (○), n = 8. The relative bone marrow and T-cell inoculum were identical in all groups. (A) Percentage of survival: • v ▪, P < .001 by Wilcoxon signed-rank test. (B) Weight after BMT as a percentage of pretransplant weight; • v ▪, P < .02 from day 28 onward; ▪ v ○, P < .05 from day 49 onward. (C) Clinical score: • v ▪, P < .005 from day 7 onward; ▪ v ○, P < .005 from day 35 onward.