MDSCs are required for Treg expansion and protection from lethal GVHD. (A) Representative dot plots gated on live donor (CD45.1+) and lineage negative (CD3−CD19−CD49b−TER-119−) cells from spleens of BALB/c recipient mice at day +10 after allogeneic HCT. Absolute and relative cell numbers of donor (B) CD11b+Gr-1high and (C) CD11b+Gr-1int MDSCs. Error bars indicate SEM. Three animals per group from 1 of 3 independent experiments are shown. (D) Representative dot plots gated on live and lineage negative (CD3-CD19-CD49b-TER-119-) cells from spleens of BALB/c mice injected with ITC or RB6-8C5. (E) Absolute number of donor Tregs re-isolated from spleens of BALB/c mice at day +10. Error bars indicate SEM. Three animals per group from 1 of 2 independent experiments are shown. (F) Overall survival of BALB/c recipient mice either depleted (RB6-8C5) or nondepleted (ITC) of MDSCs. Ten mice per group except irradiation control (n = 6). Pooled data from 2 independent experiments are shown. *P ≤ .05. ITC, isotype control antibody.
