In addition to effects on circulating cells, injury to the alve- olar–capillary interface may cause release, or allow efflux of inflammatory mediators from the alveolar space into the gen- eral circulation. Given the vast surface area of the lung in con- tact with the blood, a stimulus resulting in release of even small quantities of inflammatory mediators per cell, could re- sult in a significant influx of these mediators into the vascular space. Several investigators have also shown that increased permeability of the alveolar–capillary interface as a result of lung injury leads to the release of mediators into the circula- tion that would normally have remained compartmentalized within the alveolar space (32, 33).