RAGE expression in immune cells is required for TPA-induced dermal infiltration and epidermal hyperplasia. (A) wt and Rage^−/− mice were treated with acetone (co) or 10 nmol of TPA three times every 48 h. Representative images are shown of hematoxylin-eosin–stained skin sections derived from specimens collected 3 d after the final treatment. Dashed lines indicate the border between the epidermis and dermis. Bar, 20 μm. (B) Representative images are shown of hematoxylin-eosin–stained skin sections derived from sublethally irradiated wt mice reconstituted with bone marrow cells from wt or Rage^−/− mice (wt→wt or Rage^−/−→wt), or sublethally irradiated Rage^−/− mice reconstituted with bone marrow cells from wt or Rage^−/− mice (wt→Rage^−/− or Rage^−/−→Rage^−/−), and were treated as described in A (top two rows). Representative images of sections that were analyzed for S100a8 protein expression by IHC (brown staining; bottom two rows) and that were counterstained with hematoxylin. Dashed lines indicate the border between the epidermis and dermis. Bar, 20 μm. (C) Innate immune cells within the dermis of at least six chimeric mice of each group that were treated as described in B were counted based on specific stainings as described in Fig. 2 C. (D) Percent totals of Ki67-positive keratinocytes of skin specimens from at least three chimera of each group that were treated as described in B, measured, and analyzed as described in Fig. 1 C. Error bars represent the SEM.