Injury versus inflammatory response in the lungs of rats intratracheally inoculated with bacterial lipopolysaccharide

The relationship between acute pulmonary cell injury and inflammatory response was investigated in rats killed 1, 3, and 7 days after tracheal inoculation with bacterial lipopolysaccharide (LPS). Inoculation with LPS induced an influx of polymorphonuclear leukocytes (PMN) and a mild increase in pulmonary alveolar macrophages. Moderate, significant and time-dependent increases in LDH and AP were detected in broncho-alveolar fluid and lysate supernatant after LPS inoculations. Inoculation with saline solution alone increased PMN but did not alter LDH and AP values. The cellular influx of PMN induced by LPS was probably disproportionate to the magnitude of pulmonary cell injury.