Chimerism studies in skin biopsy. (A) Percentage of epidermal and endothelial chimeric cells in patients with or without GvHD; (▴) epidermal chimeric cells in patients with GVHD, (▵) epidermal chimeric cells in patients without GVHD, (•) endothelial chimeric cells in patients with GVHD, (○) endothelial chimeric cells in patients without GVHD. (B) Relation between apoptotic and chimeric cell numbers in epidermis, endothelium, and inflammatory infiltrate in early and late biopsies of patients with GvHD; (▵) epidermal apoptotic cells, (▴) epidermal chimeric cells,(○) endothelial apoptotic cells, (•) endothelial chimeric cells, (⋄) CD45⁺ cell, (♦) CD45⁺ chimeric cells. (C) Distribution patterns of epidermal and endothelial chimeric cells in skin biopsies of patients with GvHD; (▴) epidermal chimeric cells in superficial layers, (▵) epidermal chimeric cells in basal layers, (○) endothelial chimeric cells in upper dermis, (•) endothelial chimeric cells in deep dermis.