Dll4^hiDC-induced alloreactive T cells have reduced ability to cause GVHD. Dll4^hiDCs and GM-DCs were generated from BM of BALB/c mice. After 8 days in culture, DCs were stimulated by LPS and R848 for 24 hours. Then, both Dll4^hiDCs and GM-DCs were cultured with allogeneic B6 CD4⁺ T cells for 5 days (DCs/T cells = 1:4). Lethally irradiated (8 Gy) BALB/c mice were injected with B6 TCD-BM (5.0 × 10⁶) mixed with or without either naïve or in vitro activated allogeneic CD4⁺ T cells (1.0 × 10⁶). (A) Survival and GVHD clinical score of the recipients were monitored over time (mean ± standard error of the mean). Data shown here are pooled from 2 independent experiments. (B) Representative images show the skin, liver, and small intestine from 1 of 6 recipients in each group at day 14 after transplantation. Photographs were obtained with an Olympus BX41 microscope (10/0.3 NA lens, ×200 magnification, digital DP70 camera). (C) Graphs show the pathological scores of GVHD 14 days after HSCT (6 mice per group). **P < .01; ***P < .001.