IFN-γRKO hosts suffer early GVHD mortality. (A,B) Weight fluctuations and survival for wt syngeneic (blue), wt allogeneic (red), and IFN-γRKO allogeneic (green) recipients (≥ 12 animals per group). The P value indicates the difference between wt and IFN-γRKO hosts using the log-rank test. (C) Histologic changes associated with GVHD. Infiltration of hepatic portal tracts (pt; 200× magnification) is shown as well as cutaneous dermal (d) and epidermal (e) involvement (200× magnification). Representative sections of intestines and lung are also shown (100× magnification). (D) Histopathologic grading using a score of 0 to 4, evaluated blindly on a minimum of 3 mice per group. (E) Proportion of CD8⁺, CD4⁺, and CD11b⁺ cells in donor leukocytes recovered from the liver, intestine, and lung tissue of at least 3 mice per group, from 3 independent experiments. In histograms, data represent the mean and SD. * and *** indicate P values < .05 and < .001, respectively.