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Lung myeloperoxidase as a measure of pulmonary leukostasis in rabbits
Abstract:
Pulmonary leukostasis can be associated with acute lung injury. We studied lung peroxidase activity using myeloperoxidase (MPO) as a granulocyte marker to quantitate pulmonary leukostasis in rabbits. Lungs were homogenized in detergent, freeze-thawed, sonified, and centrifuged, and supernatants were assayed for MPO. Seven extractions were performed, and greater than 80% of cumulative MPO was found in the first three extractions. By use of a three-extraction procedure, the mean lung MPO (delta A X min-1 X g tissue-1) was determined in normal [20.9 +/- 5.2 (SE)], granulocyte-depleted (6.5 +/- 2.0), saline-injected (22.2 +/- 5.6), and pneumococcus (PNC)-challenged (69.7 +/- 10.6) animals. Lung MPO was significantly decreased in granulocyte-depleted compared with normal animals (P less than 0.005) and significantly increased in PNC-challenged compared with saline-injected animals (P less than 0.001). MPO extracted from granulocytes and lungs from normal as well as PNC-challenged animals were all biochemically identical. Lung extract did not inhibit MPO, and no MPO was detected in bronchoalveolar lavage fluid obtained from leukostatic lungs. Lung MPO significantly (P less than 0.01) correlated with intravascular intrapulmonary granulocytes. Determination of lung MPO is a relatively simple quantitative method that can be used to detect pulmonary leukostasis.
Insights
This study quantifies pulmonary leukostasis using myeloperoxidase (MPO) as a marker. Increased MPO levels in lungs indicate leukostasis, offering a simple method for detection.
Area of Science:
- Pulmonary Medicine
- Cellular Biology
- Biochemistry
Background:
- Pulmonary leukostasis is linked to acute lung injury.
- Myeloperoxidase (MPO) serves as a reliable granulocyte marker.
Purpose of the Study:
- To develop and validate a quantitative method for assessing pulmonary leukostasis.
- To measure lung myeloperoxidase (MPO) activity as an indicator of granulocyte infiltration in rabbit lungs.
Main Methods:
- Quantified lung myeloperoxidase (MPO) activity in rabbits using a three-extraction homogenization and assay procedure.
- Compared MPO levels in normal, granulocyte-depleted, saline-injected, and pneumococcus-challenged rabbits.
- Assessed the biochemical identity of MPO from different sources and its inhibition potential.
Main Results:
- Lung MPO levels were significantly lower in granulocyte-depleted animals and significantly higher in pneumococcus-challenged animals.
- MPO extracted from granulocytes and lung tissue was biochemically identical.
- Lung MPO levels showed a significant positive correlation with intravascular intrapulmonary granulocytes.
Conclusions:
- Determination of lung MPO is a simple and quantitative method for detecting pulmonary leukostasis.
- This method can aid in understanding and diagnosing acute lung injury associated with leukostasis.