What is the pathophysiology of mold-related extrinsic allergic alveolitis (EAA)?

Updated: Dec 02, 2020
  • Author: Shih-Wen Huang, MD; Chief Editor: Harumi Jyonouchi, MD  more...
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EAA encompasses a broad spectrum of pulmonary interstitial and alveolar diseases caused by repeated (occupational) exposure to a wide variety of organic dusts, microbes, and chemicals.

Repeated exposure to various molds can also cause EAA. Mold-induced EAA includes wood pulp worker's lung (Alternaria species), malt worker's lung (Aspergillus clavatus), farmer's lung (A fumigatus), maple bark stripper's lung (Cryptostroma corticale), and sewage worker's lung (Cephalosporium species).

The inflammatory process of EAA involves mast-cell activation, immune complex formation (type 3 hypersensitivity tissue injury), and influx of immune cells producing proinflammatory cytokines, such as IL-1, IL-2, IL-3, IL-12, interferon-γ (IFN-γ), and GM-CSF. The disease is likely the result of type 3 and type 4 hypersensitivity reactions.

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