Lack of donor IFN-γ results in increased pathologic GVHD in sublethally irradiated allo-HCT recipients. B6D2F1 mice received 6 Gy TBI followed the next day by administration of 3 × 10⁷ splenocytes alone or along with 10⁷ BMCs from WT or GKO B6 donors. Carcasses were preserved in formalin after death, and GVHD target tissues were prepared for pathologic examination (findings are summarized in Table 1). Liver (A) and lung (B) sections (hematoxylin and eosin; original magnification ×200) from a recipient of WT B6 splenocytes alone that died at day 14. Liver (C) and lung (D) sections (hematoxylin and eosin; original magnification ×200) from a recipient of GKO B6 splenocytes alone that died at day 17.