Recipients of Tnf^−/− donor CD4⁺ T cells display decreased bortezomib-induced GVHD-dependent lethal toxicity. BALB/c (H2^d) recipients of 15 million B6 (H2^b) Tnf^+/+ BM with or without either Tnf^+/+ or Tnf^−/− CD4⁺ T cells (5 × 10⁵) were treated with 10 μg/dose bortezomib on day +5 after BMT (n = 7-14 mice/group). Significant increases in survival (P < .005; log rank test). Combined data from 2 independent experiments are shown.