TNF-α modulates T-cell function through engagement with TNF-αRs on T cells. (A) CByB6F1 recipients were preirradiated at 5 Gy TBI and were infused with 5 × 10⁶ LN cells from WT B6 (n = 5) or TNFrsf1a^−/−1b^−/− (n = 4) donors. Recipient mice were bled and analyzed on day 13. Relative to recipients of WT B6 LN cells, recipients of TNFrsf1a^−/−1b^−/− LN cells had: (B) higher levels of BM cells, RBCs, WBCs, and platelets (PLT) (original magnification ×200; hematoxylin and eosin stain); (C) lower-level infiltration of T cells, especially CD8⁺ T cells, in recipient BM; (D) reduced intracellular IFN-γ expression in BM-infiltrated CD4⁺ and CD8⁺ T cells; (E) reduced BM proportion of effector memory (EM) CD8⁺ T cells and increased BM proportion of central memory (CM) CD8⁺ T cells; (F) reduced Fas expression on residual BM cells. *P < .05; **P < .01; ***P < .001; ****P < .0001.