TNF-α deficiency in donor effector cells does not block T-cell–mediated BM destruction. (A) CByB6F1 mice were irradiated with 5 Gy TBI without (TBI; n = 4) or with infusion of 5 × 10⁶ LN cells from WT C57BL/6 (B6 LN; n = 5) or TNF-α^−/− (TNF-α^−/− LN; n = 5) donors to induce BM failure. Animals were euthanized and evaluated at day 13. (B) Histology of sternums from CByB6F1 mice that received TBI, TBI plus B6 LN, or TBI plus TNF-α^−/− LN treatments shown as representative images (original magnification ×200; hematoxylin and eosin stain). (C) CByB6F1 mice that received LN infusion from either WT B6 or TNF-α^−/− donors developed BM failure showing reduction in BM cells, WBCs, and platelets. (D) CByB6F1 mice that received B6 LN or TNF-α^−/− LN infusion expressed high levels of Fas on whole BM cells. (E) BM cells from CByB6F1 mice that received B6 LN or TNF-α^−/− LN infusion showed reduced total CFU, CFU-GM, CFU-G, and CFU-M, relative to control mice treated with TBI only. (F) CByB6F1 mice that received B6 LN or TNF-α^−/− LN infusion had high levels of IFN-γ and TNF-α in the plasma. *P < .05; **P < .01; ***P < .001; ****P < .0001. SSC, side scatter.