OBJECTIVE The inflammatory response in Helicobacter pylori-associated gastritis (HAG) is characterized by an intense infiltrate of granulocytes and lymphocytes. The emigration of white blood cells into sites of inflammation is mediated by receptors on endothelial cells and on blood leukocytes. The aim of this study was to characterize endothelial adhesion molecule expression in HAG leading to leukocyte infiltration. METHODS Endothelially expressed adhesion molecules were studied in situ by immunohistochemical analysis of antral mucosal biopsy specimens from 20 control patients, 10 of whom had chemical gastritis, 10 normal mucosa, and 44 HAG. Adjacent biopsies were used to evaluate messenger RNA (mRNA) transcripts for the respective adhesion molecule and its inducing cytokines. RESULTS Constitutive expression of P-selectin was found in all groups. Intercellular adhesion molecule 1 (ICAM-1) was up-regulated in patients with HAG and chemical gastritis in contrast to normal controls. Vascular adhesion molecule 1 (VCAM-1) was only found within lymphoid aggregates present in HAG. Neither mRNA transcripts nor the protein product of E-selectin were detected in normal or inflamed mucosa, although mRNA of the E-selectin-inducing cytokines, tumor necrosis factor alpha and interleukin 1beta, were found. CONCLUSIONS Data suggest a major role of ICAM-1 and VCAM-1 in leukocyte-endothelial interaction in HAG without E-selectin up-regulation showing a unique pattern within the gastrointestinal tract, in contrast to observations made in inflammatory bowel disease.