Alveolar cell pattern and chemiluminescence response of blood neutrophils and alveolar macrophages in sheep after endotoxin injection.

In order to study the pathomechanisms of the Adult Respiratory Distress Syndrome in an acute animal model, we monitored the alveolar cell pattern and the stimulatory chemiluminescence responses of blood neutrophils and alveolar macrophages in sheep after Escherichia coli endotoxin injection (2 micrograms/kg of body weight). Using appropriate bronchoalveolar lavage techniques, thereby avoiding local inflammation, it was demonstrated that endotoxin injection did not cause any recruitment of neutrophils into the alveoli for a period of up to 24 hours. Following endotoxin injection, blood neutrophils showed a maximal stimulatory response after 5 minutes, and alveolar macrophages after 4 hours. It is concluded that if neutrophils are responsible for initiating the increase in microvascular permeability, then this action must be purely intravascular.