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KMID : 0350519950480030727
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Journal of Catholic Medical College
1995 Volume.48 No. 3 p.727 ~ p.734
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Neutrophil Chemotactic Activity in Bronchoalveolar Lavage Fluid of the Rats Exposed to Hyperoxia
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Abstract
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An excessive accumulation of neurophils in lung tissue has been known to play an important role in mediating the tissue injury among the adult respiratory distress syndrome, idiopathic pulmonary fibrosis and cystic fibrosis by releasing toxic
oxygen
radicals and proteolytic enzymes. Therefore, it is important to understand a possible mechanism of neutrophil accumulation in lung tissue. In many species, exposure to hyperoxic stimuli can cause changes of lung tissues very similar to human
adult
respiratory distress syndrome and neutrophils are also functioning as the main effector cells in hyperoxic lung injury.
The purpose of the present study was to examine whether neutrophils function as a key effector cell and the nature of possible neutrophil chemotactic factor found in bronchoalveolar lavage fluid. We measured the neutrophil percentage and
neutrophil
chemotactic activity in lung lavages of rats exposed to >95% oxygen. We also evaluated the molecular weight of neutrophil chemotactic factors using fast performance liquid chromatography and dialyzer membrane, and change of neutrophil chemotactic
activity after heat treatment.
@ES The results were as follows :
@EN 1. The neutrophil proportion in bronchoalveolar lavage fluid bean to rise from 48 hours group after oxygen exposure, and continued to be significantly increased with exposure time.
2. Chemotactic index for neutrophils in lung lavages from rats exposed to hyperoxia was significantly higher in 48 hours group than in cotrol group, and was significantl increased with exposure time.
3. No deaths occured until after 48 hours of exposure. However, mortality rates were 33.3% in 60 hours group and 81.3% in 72 hours group.
4. Gel filtration using fast performance liquid chromatography disclosed two peaks of neutrophil chemotactic activity in molecular weight of 104,000 and 12,000 dalton.
5. Chemotactic indices of bronchoalveolar lavage fluid were significantly decreased when bronchoalveolar lavage fluid was treated with heat (56℃ for 30 min or 100℃ for 10 min) or dialyzed (dialyzer membrane molecular weight cut off 12,000
dalton).
These results suggested that the generation of neutrophil chemotactic factor and neutrophil influxinto lung be important in hyperoxia-induced acute lung injury, and neutrophil chemotactic factor in lung lavage consist of several distinct
components
having different molecular weight and different physical characteristics.
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