The reduction in IPS severity following SCT with RANTES-deficient donor cells is associated with improved survival without significant decreases in GVHD target organ pathology. Lethally irradiated B6D2F1 mice received SCT from either syngeneic B6D2F1 (□), or allogeneic B6 wild-type (▪) or B6 RANTES-/- (▦) donors as described in Figure 3. Animals that received transplants were monitored daily for survival (A). At week 6, histopathology of the liver (B) along with the small and large bowel (C) were assessed for GVHD severity using a semiquantitative scoring system specific for each tissue. Data are expressed as mean ± SEM and are combined from 2 comparable experiments, n = 10 to 28 per group for survival data and n = 9 to 14 per group for pathology data; ^*P < .06.