Polar production of interleukin-8 by mesothelial cells promotes the transmesothelial migration of neutrophils: Role of intercellular adhesion molecule-1

Migration of polymorphonuclear neutrophils (PMNL) from the vascular compart ment into the pleural space occurs rapidly during the development of parapn eumonic effusions. This study investigated the polarized secretion of inter leukin (IL)-8 in activated pleural mesothelial cells (PMC) and the migratio n of PMNL across resting, activated PMC monolayers. Results show that PMC p roduce IL-8 in a polar manner. When PMC were stimulated with Staphylococcus aureus or IL-1 beta at the basal or at the apical surface, significantly ( P < .05) more IL-8 was released toward the apical surface. This polarized p roduction of IL-8 was confirmed by in situ hybridization. PMNL migration wa s higher from the basilar to apical than from the apical to basilar surface of PMC. Neutralizing antibodies against IL-8 and intercellular adhesion mo lecule (ICAM)-1 significantly (P < .001) blocked PMNL migration across acti vated monolayers. Thus, during pleural inflammation, PMC regulate the influ x of PMNL into the pleural space by polar production of IL-8 and expression of ICAM-1.