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Chronic experimental interstitial pneumonitis in the rabbit.
The American Review of Respiratory Disease
|January 1, 1978
Summary
Chronic aerosol antigen exposure did not cause lung disease in rabbits. However, intravenous killed bacille Calmette-Guérin (BCG) induced interstitial pneumonitis in presensitized animals, highlighting immune response differences.
Area of Science:
- Immunology
- Pulmonary Medicine
- Toxicology
Background:
- Chronic lung diseases can arise from persistent antigen exposure.
- Understanding immune responses to inhaled versus circulating antigens is crucial for lung health.
Purpose of the Study:
- To investigate the impact of chronic aerosol and intravenous antigen challenges on rabbit lungs.
- To determine if adaptive alveolar clearance protects against inhaled antigens.
- To examine the development of interstitial pneumonitis following intravenous antigen challenge.
Main Methods:
- Rabbits were pre-immunized or used as controls.
- Chronic challenges involved soluble and particulate antigens via aerosol or intravenous routes.
- Antigens included ovalbumin, keyhole limpet hemocyanin, latex particles, and killed bacille Calmette-Guérin (BCG).
- Histopathological analysis assessed lung tissue for inflammation and fibrosis.
Main Results:
- Acute alveolitis developed in sensitized rabbits after aerosol challenge, but chronic interstitial lung disease did not ensue.
- Chronic intravenous challenge with killed BCG, but not other particulate antigens, led to progressive interstitial pneumonitis.
- Fibrogenesis was observed in BCG-challenged animals presensitized to tuberculin.
- Aerosolized antigens did not cause chronic lung disease, suggesting effective alveolar clearance.
Conclusions:
- Adaptive alveolar clearance mechanisms appear to protect rabbits from chronically inhaled antigens.
- Pulmonary circulatory clearance of bacille Calmette-Guérin (BCG) can result in interstitial pneumonitis.
- This pneumonitis is dependent on prior sensitization to the antigen.