Neutrophil function in a rat model of endotoxin-induced lung injury
R. K. Simons, R. V. Maier and E. S. Lennard
Polymorphonuclear neutrophil leukocytes (PMNs) are known to cross the
alveolar-capillary barrier and enter the alveolus in acute adult
respiratory distress syndrome (ARDS). The pathogenic role of PMNs in both
the acute lung injury and subsequent infectious susceptibility in ARDS is
not clear. In the present study we investigated the functional status of
various neutrophil populations using a chronic, endotoxemia-induced ARDS
model. Rats infused with Escherichia coli endotoxin for three days develop
an acute lung injury with a histologic picture closely resembling human
ARDS. The PMNs recovered from the circulation and by bronchoalveolar lavage
were compared with normal rat PMNs. In endotoxemic animals, superoxide
production was markedly enhanced in circulating PMNs, indicating production
of high levels of potentially cytotoxic oxygen intermediates, while
myeloperoxidase activity was decreased in both circulating and lavage PMNs,
indicating depressed myeloperoxidase-dependent antimicrobial activity.
