Table 1 Differences between the alveoli and the airways

Bronchial compared with pulmonary circulation

   Structure of vessels

   Expression of adhesion molecules

   Size and hemodynamic characteristics of the site of leukocyte

   emigration

Structural differences in alveolar walls compared with bronchial walls

   Cell types present

   Anatomy and properties of the extracellular matrix

Response of structural cells at each site to inflammatory stimuli

   Mediators released (cytokines, chemokines, and others)

   Adhesion molecules expressed and used

   Contribution of biomechanical events

Stimuli and disease processes affecting alveoli compared with airways