Asbestos-body formation in the lungs of rats and guinea-pigs after inhalation of anthophyllite

Our plain-English summary of Asbestos-body formation in the lungs of rats and guinea-pigs after inhalation of anthophyllite, by S.K. Botham, P.F. Holt (The Journal of Pathology, 1972).

The study

• Authors: S.K. Botham, P.F. Holt
• Journal: The Journal of Pathology
• Published: 1972;107(4):245-52
• Cited by: 10 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Within a month after inhalation of anthophyllite some anthophyllite asbestos fibres develop into asbestos bodies in the lungs of guinea-pigs, but asbestos bodies are rarely found in rats similarly exposed even allowing a development time of 18 mth. In both species diapedesis of erythrocytes through pulmonary capillary walls occurs soon after the anthophyllite is inhaled and Perls-positive granules result. From this ferruginous material the asbestos-body coating is produced.

In both species, fibres and ferruginous material are cleared from the lungs by individual macrophages. In the guinea-pig, but seldom in the rat, some macrophages fuse in the alveolar regions to produce giant cells. The giant cells are removed less efficiently than macrophages; some block alveoli or bronchioles, others remain in the interalveolar septa. Thus the asbestos fibres and the ferruginous material required for the production of asbestos bodies are cleared more readily from the rat lung.

Ferruginous material is normally deposited on only one asbestos fibre when several are present in a cell. The fusion of several cells to form a giant cell means that more ferruginous material is available for asbestos-body formation.

PubMed has no abstract for this study. This is the authors' abstract, copied from the article.

In plain English

This animal experiment compared how asbestos bodies (fibres coated with iron-containing material) form in the lungs of rats and guinea-pigs. Ten white rats and, separately, nine guinea-pigs inhaled Finnish anthophyllite dust in a dusting tunnel. Most were exposed continuously for 24 hours, and the animals were killed at intervals over the following month. Lung sections were treated with Perls' stain, which shows iron. In both species, red blood cells escaped into the alveoli, and most fibres lying outside cells in the terminal bronchioles were cleared within 2 weeks. By the 5th day, some fibres inside guinea-pig cells had a thin iron-stained coating, which the authors described as an early stage of asbestos-body formation. No comparable stage was seen in rats. Iron-containing granules were very scarce in rats compared with guinea-pigs, and giant cells formed from macrophages were far more common in guinea-pigs. The authors concluded that the difference in how the lungs clear fibres and iron-containing material may be the sole factor. They noted that a difference between the species in the amount of iron-containing material produced could not be proved or disproved.

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: animal inhalation experiment with histological (microscope) examination of lungs, comparing rats with guinea-pigs
• Who was studied: Ten white rats (about 400 g each) and, in another experiment, nine guinea-pigs (about 500 g each), killed at intervals over about a month after the start of dusting. Control rats were killed at 0 hr and 7 days, and control guinea-pigs at 0 hr, 21 days and 28 days.
• Exposure: Inhalation of Finnish anthophyllite dust in a dusting tunnel. In each experiment one animal was killed after 3 hr of inhalation, and a second guinea-pig after a further 3 hr. The remaining nine rats and seven guinea-pigs were exposed continuously for a total of 24 hr.
• Main results:
  • In both species, most fibres lying outside cells in the terminal bronchioles were cleared by 2 weeks after dust exposure.
  • Escape of red blood cells into the alveoli was seen in both rats and guinea-pigs killed within 28 days of dusting.
  • In guinea-pigs, by the 5th day a thin pale blue (iron-stained) coating had been deposited on some fibres inside cells, which the authors regarded as an early stage of asbestos-body formation.
  • No comparable early asbestos-body stage was seen in rats, even in those killed later than 5 days after exposure.
  • Iron-containing (Perls-positive) granules inside cells were found in all rats but were very scarce compared with guinea-pigs killed at corresponding times.
  • In guinea-pigs killed from 5 days onwards, a far greater proportion of the scavenger cells in the terminal bronchioles were giant cells formed from macrophages. In rats, giant cells appeared in the bronchiolar debris only after 2 weeks.
• The authors' conclusion: The authors concluded that the difference in the clearance mechanism between the two species must affect asbestos-body production and may be the sole factor. In their view, guinea-pig macrophages fuse into giant cells that stay in the lung and pool iron-containing material, while in rats fibres and iron-containing material are cleared more readily.
• Limitations the authors state:
  • The authors stated that a possible difference in the amount of iron-containing material produced by the two species could not be proved or disproved, because quantitative experiments would be difficult to devise.

Topics

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

Medical terms in this study, explained in our Lexicon: Anthophyllite, Asbestos Bodies, Macrophage, Alveoli.

Related studies

• The effects of inhaled crocidolites from Transvaal and North-west Cape mines on the lungs of rats and guinea-pigs — S.K. Botham, P.F. Holt (1972)
• The development of glass-fibre bodies in the lungs of guinea-pigs — S.K. Botham, P.F. Holt (1971)
• Lung cell reactions in guinea pigs after inhalation of asbestos (amosite) — M. Sjöstrand, R. Rylander, et al. (1989)
• Comparison of effects of glass fibre and glass powder on guinea-pig lungs — S.K. Botham, P.F. Holt (1973)
• Biochemical changes and pulmonary response of guinea pigs to asbestos dust — J. Singh, M.U. Beg, et al. (1976)
• Development of asbestos bodies on amosite, chrysotile and crocidolite fibres in guinea-pig lungs — S.K. Botham, P.F. Holt (1971)

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