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Eosinophil- and eosinophil granule-mediated pneumocyte injury
The Journal of Allergy and Clinical Immunology
|October 1, 1985
Summary
Eosinophils can damage lung cells through direct contact, causing detachment and potential lysis, which may worsen inflammatory lung diseases like asthma. This damage is mediated by granule proteins, not oxygen radicals.
Area of Science:
- Pulmonology
- Cell Biology
- Immunology
Background:
- The role of eosinophils in asthma and eosinophilic pulmonary syndromes remains unclear.
- Investigating the potential harmful effects of eosinophils on lung tissue is crucial for understanding these diseases.
Purpose of the Study:
- To determine if eosinophils and their products cause damage to alveolar epithelial cells.
- To elucidate the mechanisms by which eosinophils injure pneumocytes.
Main Methods:
- Cultures of human eosinophils, eosinophil major basic protein (MBP), and granule fractions with A549 and rat type II pneumocytes.
- Assessing cell lysis and nonlethal cell detachment as measures of damage.
- Investigating the role of oxygen radicals and specific granule components in mediating injury.
Main Results:
- Activated intact eosinophils caused nonlytic detachment of pneumocytes, requiring close cell contact and not dependent on oxygen radicals.
- Purified eosinophil major basic protein (MBP) caused significant pneumocyte lysis.
- Different eosinophil granule fractions induced distinct injuries: lysosomal enzymes and eosinophil peroxidase caused detachment, while MBP caused lysis.
Conclusions:
- Intact eosinophils can mediate nonlytic detachment of alveolar pneumocytes via granule products, likely lysosomal enzymes.
- Eosinophil major basic protein (MBP) can cause pneumocyte lysis at sufficient concentrations.
- Eosinophil-induced damage to alveolar epithelial cells may increase lung permeability and enhance immune sensitization in pulmonary diseases.
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