IDO-deficient donor pDCs induce more severe GVHD activity. Survival (A) and mean GVHD scores (B) of mice that received 3 × 103 HSCs + 3 × 105 B6 splenic T cells (n = 15), and groups that also received 5 × 104 pre-pDCs from WT donors (n = 15) or IDO1−/− donors (n = 12), in the C57BL/6J→BA.B10 transplant model. Data are means ± SEM from 3 replicate experiments with 5 to 6 mice per group. (C-E) T-cell chimerism analyses of animals from panel A, showing blood T cells derived from mature T cells in the graft (C), donor HSC-derived T cells (D), and residual host T cells (E). Day 0 values for host T cells were determined using 3 mice that were irradiated and then bled 2 days later, with absolute T-cell levels averaging 3% of control. Day 10 values were determined from a separate experiment with recipient mice killed at this time point (n = 3). Survival (F) of mice transplanted using the same conditions as in panel A and also injected with 1 × 105 viable LBRM tumor cells at day −1. Data from 4 independent experiments are combined. n = 30 mice in both the HSCs + T cell and the HSCs + T + WT pre-pDC groups and n = 9 in the HSC + T + IDO1−/− pre-pDC group (*P < .01 comparing recipients of T cells and WT pre-pDCs with recipients of T cells and IDO1−/− pre-pDCs).
