cDC development is disrupted during GVHD. (A) BALB/c recipients of B6.CD11c.DTR BM + T donor grafts were treated with DT on days 12, 14, and 16 after transplantation to deplete donor cDCs. TEa Tg T cells were transferred on day 14, and proliferation was analyzed 3 days later as described. Data are combined from 2 replicate experiments: n = 8/group (saline) and n = 6/group (DT). *P = .0406. (B) Splenic DCs were enumerated at day 10 after transplantation (B6 → BALB/c model); n = 9/group. **P = .04. (C) cDC subset analysis was performed. FACS plots illustrate the CD8/CD4 expression profiles of naive WT.B6 CD11c⁺MHC class II^high cDCs and of day 10 post-transplantation cDCs (B6 → BALB/c system). (D) DCs were enriched by density gradient centrifugation, and phenotype was assessed by flow cytometry; n = 5/group. *P = .05 to .01. **P = .01 to .001. (E) BMTs were performed in the C3H/Hej → B6 and the B6 → B6D2F1 models (described in “BMT”), and DC subsets were analyzed at day 10 after transplantation. (F) cDC subsets at day 6 and 8 after transplantation. (G) Irradiated BALB/c mice (900 cGy) received 5 × 10⁶ WT.PTPrc^a TCD BM (CD45.1) + 5 × 10⁶ B6.MHC class II^−/− TCD BM ± 0.2 × 10⁶ WT.PTPrc^a CD4⁺ T cells on day 0. Splenic DCs were enriched by density gradient centrifugation and analyzed by flow cytometry on day 10. (H) Data demonstrate the ratio of CD45.1 (WT) to CD45.2 (MHC class II^−/−) DCs. Combined data from 2 replicate experiments; n = 10/group. (I) TCD Bcl2 Tg donor BM was transferred with or without T cells, and DC subsets were assessed on day 10 after transplantation as described; n = 5/group.