Administration of Mn exacerbates acute GVHD after allogeneic BMT. (A-B) Lethally irradiated B6D2F1 mice were transplanted with 4 × 10⁶ TCD-BM cells plus 4 × 10⁶ T cells from allogeneic (Allo) B6 donors or syngeneic (Syn) donors on day 0, followed by single intaperitoneally injection of Mn (1 mg/g body weight) or PBS. Survival (A) and clinical GVHD scores (B, means ± standard error) of Syn controls (open circles), Mn-treated Syn (open diamonds), Allo controls (closed circles), and Mn-treated Allo (closed diamonds) from 3 independent experiments were combined (n = 12-15 per group). (C-D) Lethally irradiated B6 mice were transplanted from C3H.Sw donors. Survival (C) and clinical GVHD scores (D, means ± standard error) of Allo controls (open circles) and Mn-treated Allo (closed circles) from 3 independent experiments were combined (n = 9 per group). (E) Lethally irradiated WT or Dectin-2^−/− B6 mice were transplanted with cells from BALB/c donors. Survival of WT controls (open circles), Dectin-2^−/− controls (open diamonds), Mn-treated WT mice (closed circles), and Mn-treated Dectin-2^−/− mice (closed diamonds) from 3 independent experiments were combined (n = 6-10 per group). (F) Lethally irradiated B6D2F1 mice were transplanted with BM and T cells from WT or Dectin-2^−/− B6 donors. Survival of Allo controls with WT donors (open circles), Allo controls with Dectin-2^−/− donors (open diamonds), Mn-treated mice with WT donors (closed circles), and Mn-treated mice with Dectin-2^−/− donors (closed diamonds) from 2 independent experiments were combined (n = 5-10 per group). *P < .05; **P < .01.