Allogeneic T cells stimulated with host-type MLN DCs in vitro induced the highest GVHD mortality and morbidity after bone marrow transplantation in vivo. (A) Naive allogeneic donor T cells stimulated with organ-derived host-type dendritic cells in vitro were used as donor T cells in an MHC-mismatched B10.BR into C57BL/6 murine BMT model with T cell–depleted 5 to 10 × 10⁶ BM cells and 10⁶ T cells (n = 28-32, 4 combined experiments). Survival was significantly shorter for the MLN DC group (*MLN vs liver/PLN: P < .001, MLN vs spleen: P = .001) with 40 days median survival for spleen-derived dendritic cells, 39 days for liver-derived dendritic cells, 39 days for PLN DCs, and 31 days for MLN DCs. (B) Clinical GVHD score (*MLN vs spleen/PLN: P < .001, MLN vs liver: P = .024) and (C) weight curves (*MLN vs spleen/PLN: P < .001, MLN vs liver: P = .013) show higher GVHD morbidity for the MLN DC group. (D) Histopathologic analysis of the GVHD target organs skin, liver, and small and large bowel at day 14. There is a trend toward higher GVHD scores in the small and large bowel of the MLN DC group (*MLN vs liver/PLN: P < .05, **MLN vs liver: P < .05). (E) Levels of IFN-γ and (F) liver function tests at day 14 on sera of mice that underwent transplantation are comparable among all groups. Error bars represent SEM.