Figure 1

"Schematic representation of trans-epithelial loss of leukocytes into airway lumen". Modified from references [61, 16, 112]. This scheme identifies some of the steps where future research is warranted to delineate mechanisms involved in the trans-epithelial elimination of inflammatory cells from the airway wall. 1 After cell-to-cell contact at the epithelial base paraepithelial crawling of the leukocyte may begin by integrin binding to desmosomal junction adhesion molecules. 2 Several binding interactions and cellular signalling events including cytosolic Ca++ fluxes may be involved as the leukocyte continues to migrate between juxtapositioned epithelial cells. 3 Binding interactions involving junction adhesion-like proteins and receptors such as the coxsackie and adenovirus receptor may be involved in protein-tight passage of the leukocyte through the tight apical junction complex. 4 After its elimination from the airway wall the leukocyte mixes with epithelial lining fluids and is finally eliminated by mucociliary clearance.