Id2-deficient T cells do not induce GVHD. T-cell–depleted bone marrow from B6 or Ly5.1⁺ mice was mixed with 0.5 to 1 × 10⁶ wild-type (B6 or Il10^gfp/+) or Id2-deficient (Id2^fl/flLck^Cre+ or Id2^fl/flLck^Cre+Il10^gfp/+) T cells and then transferred into irradiated BALB/c mice. (A) Kaplan-Meier survival curve of recipient mice. Data are pooled from 3 or 4 independent experiments. Statistically significant differences of survival were determined using a log-rank test. (B) Representative hematoxylin and eosin–stained sections of the colon 4 weeks after mice had received T cells (*, intestinal necrosis). Representative images from 2 independent experiments. (C) Number of Ly5.2^+/+CD44⁺ CD4⁺ and CD8⁺ T cells in the spleen, liver, and colon 7 days or 30 to 35 days after T-cell transfer (day 7, data pooled from 4 experiments; n = 10-11 mice per genotype; 30 to 35 days, data pooled from 2 experiments, n = 5-6 mice per genotype). Statistically significant differences were determined using the Mann-Whitney U test; * P < .05; ns, not significant. (D) Flow cytometric analyses of IL-10-GFP expression in Ly5.2⁺CD4⁺ or CD8⁺ T cells from spleen and liver of BALB/c mice 7 days after adoptive transfer of Ly5.2⁺Il10^gfp/+ or Id2^fl/flLck^Cre+Il10^gfp/+ T cells. (E) Intracellular granzyme B expression in wild-type and Id2^fl/flLck^Cre+ CD8⁺ T cells 7 days after T-cell adoptive transfer (red line, Ly5.2⁺CD8⁺ T cells; black line, Ly5.1⁺ bone marrow–derived donor cells). (F) Frequency of IL-10-GFP⁺ cells of Ly5.2⁺ CD44⁺ CD4⁺ and CD8⁺ T cells in the spleen, liver, and colon 7 or 30 to 35 days after T-cell transfer (n = 5-6 mice per genotype pooled from 2 separate experiments). Statistical differences were determined using an unpaired 2-tailed Student t test; *P < .05; **P < .01; *** P < .001; ns, not significant. (G) Weight loss curves in lethally irradiated BALB/c mice reconstituted with Ly5.1^+/+ bone marrow cotransferred with wild-type or Id2-deficient T cells as in panel A. IL-10R blocking antibody or control antibody was injected intraperitoneally 4 days after T-cell transfer. Mice sacrificed due to severe weight loss (>20%) or clinical symptoms are indicated by a cross. Statistical differences were determined using an unpaired 2-tailed Student t test; **P < .01; *** P < .001; ns, not significant. Ab, antibody; BM, bone marrow; GzmB, granzyme B; WT, wild-type.