Incidence of scleroderma in the presence or absence of donor-derived IL-17. (A) Lethally irradiated recipient B6 mice were transplanted with grafts from G-CSF–treated WT (n = 9) or IL-17A^−/− (n = 11) BALB/c donors. Non-GVHD recipients received T-cell-depleted WT grafts (n = 4). Histologic scoring of parameters of scleroderma 70 days after transplantation as detailed in “Histology and immunostaining of GVHD target organs.” Data represent mean ± SEM pooled from 2 replicate experiments. (B) Representative images (original magnification ×400) of hematoxylin and eosin or Masson (which stains collagen blue) stained paraffin sections of skin taken 70 days after transplantation. (C-D) Lethally irradiated recipient B6 mice were transplanted with grafts from G-CSF–treated WT or IL-17A^−/−BALB/c donors (n = 6 per group). Non-GVHD recipients received T-cell-depleted WT grafts (n = 3). Histologic scoring of parameters of inflammation in skin 28 days after transplantation as detailed in “Histology and immunostaining of GVHD target organs.” Representative images of cellular infiltration within skin from B6 recipients of BALB/c grafts from G-CSF–treated WT or IL-17A^−/− donors at day 28 and day 70 after SCT. Macrophages (F4/80⁺) and T cells (CD3⁺) are stained brown. Neutrophils are stained red (arrow) by chloroacetate esterase Leder stain. **P < .01, *P < .05, WT vs IL-17A^−/− grafts.