PLASMA EXUDATION AND SOLUTE ABSORPTION ACROSS THE AIRWAY MUCOSA

The airway mucosa responds to inflammatory provocations with bulk exud ation of plasma into the airway tissue (vascular exudation) and lumen (mucosal exudation). The intensity and time course of the exudative re sponse can be relevantly examined by sampling and analysing airway sur face liquids, because the luminal entry of plasma proteins/tracers pro mptly and quantitatively reflects the exudative response of the airway s. The process of mucosal exudation of plasma is a prominent feature o f airway inflammation and has been demonstrated in rhinitis, asthma, a nd bronchitis. Inflammatory mediators and allergen produce mucosal exu dation of plasma into the airway lumen (outward permeability) whereas the solute absorption across the mucosa (inward permeability) is unaff ected. Hence, in contrast to current views, we have demonstrated that in airway inflammation the solute absorption across the airway mucosa is not increased. The findings suggest the plasma exudation response a lso as a first line respiratory mucosal defence, allowing potent plasm a protein systems to appear on an airway mucosa functionally intact as a barrier toward undue luminal material. Our data on plasma exudation and solute absorption across the mucosa of upper and lower airways fu rther suggest the human nasal airways as a model relevant also for the tracheobronchial airways.