TLR signaling is not required for pDCs to prime alloreactive T cells. (A) A total of 2 × 10⁵ BALB/c CD4⁺ T cells were cultured with 10⁴ WT or TRIF/MyD88 DKO (DKO) pDCs with or without CpG 1668 1 μM (left) or LPS 10 μg/mL (right) to determine cell proliferation. Data are shown as mean (± SD). (B,C) CFSE-labeled BALB/c CD4⁺ T cells (H-2K^d) were transferred to irradiated H2-Ab1^−/− mice preinjected with pDCs or cDCs isolated from WT or DKO B6 mice. Cell divisions of H-2K^d+ donor CD4⁺ cells in the spleens (B) and GVHD pathology scores in the liver and intestine (C) are shown. Data from 3 similar experiments are combined and shown as means plus or minus SEM (n = 7). *P < .05.