Adoptive transfer of in vitro mATG-stimulated cells inhibits GVHD and expansion of allogeneic CD8⁺ T cells. Normal C57BL/6 splenocytes treated with either mATG or rabbit IgG and IL-2 for 5 days were adoptively transferred into recipient RAG-2 KO mice at 2.5 to 5 × 10⁷ cells/mouse 1 day prior to induction of acute GVHD by injection of fresh, normal allogeneic C57BL/6 splenocytes as described in the “Acute graft-versus-host disease induction.” (A) Percentage weight change and (B) percentage survival of the animals at various times following induction disease. (C) Serum ALT and AST levels at 3 weeks of disease. (D) Blood CD4⁺ and CD8⁺ T-cell percentages 1 week following disease induction. Data for weight change, serum AST and ALT levels, and blood T-cell populations are expressed as means (± SD). Survival data are pooled from 3 experiments with a total of 20 mice. Data for weight change and serum liver enzymes (AST and ALT) are representative of 3 experiments containing at least 6 mice per group. Statistically significant differences (P < .05) between transfer of mATG-treated splenocytes and control splenocytes was observed in 2 of 3 experiments for weight change and in all 3 experiments for serum liver enzymes. T-cell populations were evaluated in 2 of the 3 experiments with both showing statistically significant differences (P < .01) between groups receiving mATG-treated splenocytes compared with control splenocytes.