MDSC cotransplantation skews T cells towards a type 2 phenotype. (A) Lethally irradiated B6.bm1 recipient mice were reconstituted with TCD-BM from B6 mice with or without B6-derived SCs in the presence or absence of 1 × 10⁷ B6-derived MDSCs. TNF-α, IFN-γ, and IL-5 concentrations were determined in the serum of transplanted animals 10 days after BMT. (B-E) Lethally irradiated B6.bm1 recipient mice (H-2K^bm1, CD45.2⁺) were reconstituted with TCD-BM from B6 mice (H-2K^b, CD45.2⁺) plus B6.SJL-derived SCs (H-2K^b, CD45.1⁺) in the presence or absence of 1 × 10⁷ B6-derived MDSCs (H-2K^b, CD45.2⁺). Ten days after transplantation, mice were euthanized and CD45.1⁺ allogeneic T cells were isolated. qRT-PCRs for the expression of cytokines (B) and transcription factors (C) in allogeneic T cells were performed, and relative expression to AIP was calculated. Ten days after BMT, SCs from mice reconstituted with allogeneic BM and SCs in the presence or absence of MDSCs were re-stimulated with PMA/iono. Cells were stained for surface markers CD45.1, CD3, CD4, and CD8. Percentage of CD45.1⁺CD3⁺CD8⁺ T cells expressing IL-5, IL-13, IFN-γ, and TNF-α was determined by intracellular stainings (D). Ten days after transplantation, mice were euthanized and CD45.1⁺ allogeneic T cells were isolated from lung and liver. qRT-PCRs for the expression of IL-4, -5, -13, IFN-γ, TNF-α (top) and STAT6, GATA-3, STAT4, and T-bet (bottom) were performed, and relative expression to AIP was calculated (E). Data represent the mean value ± SD of triplicates from spleens of at least 5 mice pooled (B-C). (D) Shows the mean value ± SD of 3 experiments with SCs pooled from 3 mice. (E) Shows the mean value ± SD of 2 experiments with lung and liver cells pooled from at least 6 mice. *P ≤ .05; **P ≤ .01; ***P ≤ .001. n.s., not significant.