Concentrations of interleukin (IL)-8, a potent chemotactic factor produced by many cell types, are elevated in the peritoneal fluid of women with endometriosis. We investigated whether endometrial stromal cell (ESC) adhesion induces the expression of IL-8 and if this process is integrin-mediated. ESCs were plated onto culture dishes coated with various extracellular matrix (ECM) substrates, such as fibronectin, laminin, collagen IV, and poly-L-lysine, or mouse anti-human integrin beta(1,) and beta(2) monoclonal antibodies. IL-8 expression was induced by adherence of ESCs to fibronectin or collagen IV, but not to poly-L-lysine, a non-integrin-dependent adhesion matrix. Engagement of beta(1)-containing integrins was associated with ESC adhesion and resulted in up-regulation of IL-8 mRNA expression and protein secretion. Disruption of the actin cytoskeleton by treating ESC with cytochalasin D completely blocked the increase of IL-8 that was induced in response to integrin activation. These findings indicate a novel mechanism of IL-8 regulation; cell adhesion to ECM is an important event that leads to stimulation of IL-8 expression, and this process is mediated by integrins.