SMAD3 deficiency in both T and non-T cells contributes to lethal GVHD. (A) Representative photographs of colon sections stained with anti-CD3ϵ, anti-F4/80, and anti-Gr-1 (100-μm scale unit). Virtual slides were scanned with the NanoZoomer, Version 2.0 series system and acquisition software NDP.scan, Version 2.2.17 (Hamamatsu Photonics) using a 40× objective lens. (B) One representative plot of CD8/CD4 and Gr-1/CD11b staining of colon cells. (C) Mean percentages of CD4⁺ and CD8⁺ cells and (D) of granulocytes (CD11b⁺/Gr-1⁺) and monocytes (CD11b⁺/Gr-1⁻) among the live gate. All histograms represent means with error bars representing SEM. Statistical analyses were performed with Student t test: *P < .05. (E) Splenocytes from either WT or SMAD3-KO mice were admixed to T cell-depleted BM from WT or SMAD3-KO 129-strain donors and injected into BALB.B recipients. Survival curves were analyzed using the log-rank test. Survival of mice that received mixed grafts (in which only the BM or the spleen cells were from SMAD3-KO donors) was better than for recipients of SMAD3-KO graft (P < .05), but worse than for recipients of WT graft (P < .05).