GPR109A^−/− T cells cause less GVHD than WT T cells. (A) Survival and clinical GVHD scores of lethally irradiated C57BL/6 (B6) or Gpr109a^−/− recipients transplanted with 5 × 10⁶ T cell-depleted bone marrow (BM) cells and 1 × 10⁶ LP/J splenic T cells (LP BM + T). Controls were transplanted with T cell-depleted BM only (LP BM). (B) Survival and clinical GVHD scores of lethally irradiated BALB/c mice transplanted with 5 × 10⁶ T cell-depleted BM cells and 1 × 10⁶ WT T cells (B6 + B6 T cells), WT BM with Gpr109a^−/− T cells (B6 BM + Gpr109a^−/− T), or Gpr109a^−/− BM with WT T cells (Gpr109a^−/− BM + B6 T). Controls were transplanted with T cell-depleted BM only (B6 BM) or Gpr109a^−/− BM only (Gpr109a^−/− BM) in a major (B6 into BALB/c) MHC-mismatched model of GVHD. (C) Same as in B, in a minor antigen mismatched, MHC-matched model of GVHD (B6 into 129S1). (D) BM chimeras, WT B6 Ly5.2 into Ly5.1 or Gpr109a^−/− Ly5.2 into Ly5.1 were used as donors. Survival and clinical GVHD scores of lethally irradiated BALB/c mice transplanted with 5 × 10⁶ WT T cell-depleted BM cells and 1 × 10⁶ WT T cells ([B6 → Ly5.1] BM + [B6 → Ly5.1] T) or WT T cell-depleted BM with Gpr109a^−/− T cells ([B6 → Ly5.1] BM + [Gpr109a^−/− → Ly5.1] T). Controls were transplanted with WT ([B6 → Ly5.1] BM) or Gpr109a^−/− T cell-depleted BM ([Gpr109a^−/− → Ly5.1]) only. (E) Lethally irradiated BALB/c mice transplanted with 5 × 10⁶ WT T cell-depleted BM cells, 1 × 10⁶ A20 tumor cells, and 0.5 × 10⁶ WT (B6 BM + B6 T + A20) or Gpr109a^−/− T cells (B6 BM + Gpr109a^−/− T + A20). Controls were transplanted with WT T cell-depleted BM and A20 tumor cells (B6 BM + A20) only. Cause of death is plotted in the table to the right. Comparisons of groups for survival curves in (A) to (E) were performed by Mantel-Cox log rank test for survival. For GVHD scores, data represent the mean ± standard error, comparison of groups performed by two-way ANOVA. All results from two to three independent experiments.