Electron-microscope studies of asbestosis in man and animals

Our plain-English summary of Electron-microscope studies of asbestosis in man and animals, by J.M. Davis (Annals of the New York Academy of Sciences, 1965).

The study

• Author: J.M. Davis
• Journal: Annals of the New York Academy of Sciences
• Published: 1965;132(1):98-111
• Cited by: 55 articles, as counted by NIH iCite
• Read it: PubMed · Publisher
• In J-M's library: Johns-Manville's company medical library held a copy.

In plain English

This article described electron-microscope examination of lung tissue from rats and guinea pigs dusted with chrysotile, and of two lung biopsies from patients with asbestosis. In guinea pigs, changes occurred in three stages: giant cell lesions near terminal bronchioles, then widely scattered fibrosing interstitial pneumonia, often followed by complete consolidation in some areas. Chrysotile was first seen only inside alveolar macrophages, which joined to form giant cells and could convert into fibroblasts. Human tissue showed very similar lesions. Asbestos bodies, coated mainly with ferritin granules, were found only in macrophages, fibroblasts, or embedded in collagen. Many guinea pig fibers stayed uncoated after at least 15 months in the lung. Most dust in both human and guinea pig lungs was very small. The author concluded that asbestosis seems basically an intracellular process, with alveolar macrophages and their derivatives the only cells directly involved. The author also suggested that, if the coating protects tissue, uncoated dust may cause the damage. Preliminary animal experiments suggested that fine particles alone may be just as damaging as dust containing both large and small particles.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Descriptive electron-microscope study of lung tissue from experimentally dusted animals and from human biopsies
• Who was studied: Rats and guinea pigs from P. F. Holt's experimental asbestosis study at Reading University (number of animals not stated), and two lung biopsy specimens from patients with asbestosis
• Exposure: Animals were dusted with chrysotile (dust doses not given). The human lung tissue contained both amphibole (including amosite) and chrysotile particles.
• Main results:
  • In guinea pigs, lung changes occurred in three successive stages. First came giant cell lesions, usually in the walls of terminal bronchioles. Then came a widely scattered fibrosing interstitial pneumonia, which was often followed by complete consolidation in some areas.
  • In the dusted animals, giant cells formed from dust-containing macrophages, and these macrophages could convert into fibroblasts
  • In the animals, most fibroblasts in fibrotic areas contained chrysotile dust
  • The human lung material showed lesions very similar to those in the experimental animals
  • Partly or completely formed asbestos bodies were found in only three sites: alveolar macrophages, fibroblasts, or embedded among collagen fibers in fibrotic areas
  • In human material, the asbestos body coating consisted mainly of ferritin granules, as in guinea pigs
  • In guinea pigs, coating was not inevitable. Many uncoated fibers were found in the oldest animals, whose fibers had been in the lung for at least 15 months, while some bodies formed after as little as eight weeks of dusting.
  • Irregular bodies were found in macrophages of guinea pigs and humans. These were clusters of ferritin granules with small asbestos crystals scattered through them and no definite fiber core.
  • In the human specimen, amosite particles in macrophages showed frequent signs of breaking down into needle-like fragments, which the author thought were likely incorporated into asbestos body coats
  • Most of the dust reaching both human and guinea pig lungs had a very small particle size
  • Very little free dust was found in the human biopsy material, although both patients had been exposed until within a few weeks of biopsy
  • Preliminary results from ongoing animal experiments using only fine asbestos particles suggested that fine dust may be just as damaging as dust containing both large and small particles
• The authors' conclusion: The author concluded that asbestosis seems to be basically an intracellular process, with alveolar macrophages and their derivatives the only cells directly involved. The author also suggested that, if the coating protects tissue, uncoated dust may be what causes the damage.
• Limitations the authors state:
  • Human lung material was difficult to obtain, and only two biopsy specimens were available
  • One of the two human biopsy specimens contained little dust

Topics

The National Library of Medicine indexes this study under subjects our site covers: Asbestosis.

Related studies

• The effects of chrysotile asbestos dust on lung macrophages maintained in organ culture. An electron-microscope study — J.M. Davis (1967)
• The long term fibrogenic effects of chrysotile and crocidolite asbestos dust injected into the pleural cavity of experimental animals — J.M. Davis (1970)
• Quantitative assessment of inorganic fibrous particulates in dust samples with an analytical transmission electron microscope — F.D. Pooley, N.J. Clark (1979)
• An electron microscopy study of the effect of asbestos dust on the lung — J.M. Davis (1963)
• Preparation of extrapulmonary tissues and body fluids for quantitative transmission electron microscope analysis of asbestos and other mineral particle concentrations — P.M. Cook (1979)
• The effect of different mineral dusts on the mechanism of phagocytosis: a scanning electron microscope study — K. Miller, R.I. Handfield, et al. (1978)

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