Transmigration of human neutrophils across airway epithelial cell monolayers is preferentially in the physiologic...

To study the mechanisms involved in the movement of neutrophils from the blood stream into the lung airways, we investigated human neutrophil transmigration across a monolayer of human airway epithelial cells, both in the apical-to-basolateral direction and in the more physiologic basolateral-to-apical direction. Migration of human neutrophils across monolayers of human airway epithelial H292 cell-line cells and primary bronchial epithelial cells occured most efficiently in the basolateral-to-apical direction, both after the addition of chemoattractants to resting epithelial cells and across interleukin-1beta (IL-1beta)-stimulated epithelial cells. Blocking studies with monoclonal antibodies revealed that the migration of neutrophils was mediated by the CR3 adhesion molecule (CD11b/CD18) on the neutrophils. IL-1beta-treated epithelial cells caused neutrophil movement via the secretion of chemoattractants. The most potent chemoattractant released by the epithelial cells was found to be IL-8, because the IL-1beta-induced migration was inhibited for 75 +/- 10% by the addition of an antibody against IL-8. After apical stimulation of the epithelial cells with an optimal concentration of IL-1beta, 27 +/- 4 ng/ml IL-8 was found in the supernatant at the apical side of epithelial cells. Platelet-activating factor (PAF) synthesis by the epithelial cells did not play a role in neutrophil transmigration, as was demonstrated by the lack of inhibition of this process after addition of the PAF-receptor antagonist WEB 2086. We conclude that the movement of neutrophils across airway epithelial cell monolayers occurs preferentially in the physiologic basolateral-to-apical direction, indicating that the polarity of epithelial cells is important for neutrophil transmigration.