Expression of CXCL10 and CXCR3 in skin biopsies from patients with aGVHD and control patients. A representative example from 11 patients with GVHD and 5 control patients. Single enzymatic staining for CXCL10 (ligand; brown stain) showed significant expression of CXCL10 in basal keratinocytes of the epidermal (e) layer of aGVHD skin versus no expression on control tissue. CXCR3 expression (brown stain) was located to the dermal (d) infiltrates located in close proximity to the epidermis in aGVHD skin. Control tissue lacked these infiltrates but showed some CXCR3 expression on scattered T cells within the dermis. Arrows indicate positive staining. See “Immunohistochemistry” for complete image acquisition information.