The mechanisms that lead to the development of skin lesions in patients with dermatitis herpetiformis (DH) are not known. We hypothesized that an ongoing immune response in the gut of patients with DH would result in an increase in circulating cytokines and be associated with endothelial cell activation, creating a proinflammatory environment in the skin. Skin biopsies from the normal-appearing inner arm of 11 DH patients, with no active skin lesions, and 12 normal subjects were analyzed for E-selectin (E-sel) and ICAM-1 mRNA. DH patients' skin expressed markedly increased levels of E-sel mRNA. Mean E-sel mRNA expression in DH skin was 1,271 (range 63.78-5861) times greater than that of a control, normal skin (P<0.001) with no significant increased expression of ICAM-1 mRNA. Serum levels of soluble E-selectin (sE-sel), IgA anti-tissue transglutaminase antibodies, and serum IL-8 levels were significantly increased in patients with DH. These studies demonstrate that patients with DH have evidence of endothelial cell activation in the skin and systemic manifestations of the ongoing inflammation associated with the mucosal immune response. Endothelial cell activation may play a critical role in the development of skin lesions in patients with DH and may represent a common mechanism for cutaneous manifestations of inflammatory gastrointestinal diseases.