Further observations on the ultrastructure and chemistry of the formation of asbestos bodies

Our plain-English summary of Further observations on the ultrastructure and chemistry of the formation of asbestos bodies, by J.M. Davis (Experimental and Molecular Pathology, 1970).

The study

• Author: J.M. Davis
• Journal: Experimental and Molecular Pathology
• Published: 1970;13(3):346-58
• Cited by: 45 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

The examination of pleural granulomas during the first 14 days after the injection of chrysotile asbestos dust in experimental animals produced new evidence on the formation of asbestos bodies. In those species which produced bodies readily, the longer dust fibers were seldom phagocytosed by a single macrophage, but were surrounded by macrophages which eventually fused to form giant cells. It is while dust fibers were surrounded by partially fused macrophages that the earliest signs of body coating were seen. It is therefore suggested that only those fibers that are retained in a site of partial fusion for some time ever become coated. The coating process probably ceases when fusion is complete and the body is completely enclosed in a fully formed giant cell. The first coating material of the asbestos bodies seems to be some form of acid mucopolysaccharide, but this coating soon becomes impregnated with ferritin or hemosiderin to form the well-known Perls-positive bodies.

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

In plain English

This animal experiment examined how asbestos bodies (coated asbestos fibers) begin to form. Chrysotile asbestos dust was injected into the chest (pleural) cavity of guinea pigs and rats (25 mg) and mice (10 mg). Animals were killed 7 days to 6 months later, and the pleural lesions were examined by light and electron microscopy. On iron-stained light-microscope sections, guinea pigs had many bodies by 14 days, mice a few by 3-4 weeks, rats none; electron microscopy found more mouse bodies, whose coatings often held fewer iron granules. In guinea pigs the first coating appeared after 9-10 days as low-density material resembling mucopolysaccharide. It formed in clefts between macrophages (scavenger cells) fusing into giant cells, not inside complete giant cells; a few times a single macrophage wrapped one end of a long fiber and coated that part. By 14 days the coating was filling with small dense iron-containing granules. In rats, the author suggested a dense reticulin network probably kept macrophages from fusing. The author concluded that asbestos body formation likely depends first on a mucopolysaccharide coating, which staining could not confirm.

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 experiment: chrysotile dust was injected into the pleural cavity, animals were killed at intervals from 7 days to 6 months after injection, and the pleural lesions were examined by light and electron microscopy
• Who was studied: Guinea pigs, rats and mice. The number of animals is not stated
• Exposure: Chrysotile asbestos dust injected into the lower right pleural cavity: 25 mg for guinea pigs and rats, 10 mg for mice, suspended in 1 ml of distilled water
• Main results:
  • Guinea pigs: large numbers of asbestos bodies were seen with Perls' stain (light microscopy) by 14 days after injection
  • Mice: a few asbestos bodies were found with Perls' stain by 3-4 weeks
  • Mice: electron microscopy found more asbestos bodies than Perls'-stained light microscopy indicated, because mouse bodies often contained many fewer ferruginous (iron-containing) granules than guinea pig bodies
  • Rats: no asbestos bodies were found at any time during the study
  • Guinea pigs: the earliest signs of fiber coating were seen by electron microscope after 9-10 days, as low-density material resembling mucopolysaccharide
  • The early coating formed in clefts between individual macrophages during giant cell formation, not inside fully formed giant cells
  • In a few cases no giant cell formed, and a single macrophage partly engulfed a long fiber by wrapping around one end; a coating was laid down on the part the cell covered
  • By 14 days after injection the coating was becoming impregnated with small dense granules similar to ferritin or hemosiderin
  • Rats: the author suggested that a dense reticulin network separating the macrophages probably explained their inability to fuse into giant cells, and so the lack of asbestos bodies
• The authors' conclusion: The author concluded that it seems likely that asbestos body formation depends first on a coating of mucopolysaccharide, which later becomes impregnated with iron-containing material from surrounding cells. The author proposed that coating happens between partly fused macrophages, so it is neither a fully intracellular nor a fully extracellular process.
• Limitations the authors state:
  • The author states that the coating material could not be confirmed as mucopolysaccharide by histochemical staining, because so much of this material was present throughout the granulomas
  • The author states that the exact nature of the dense granules in the coating is not yet known
  • The author's theory of body formation rests on three assumptions

Topics

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

Medical terms in this study, explained in our Lexicon: Asbestos Bodies, Granuloma, Chrysotile, Macrophage, Ferritin.

Related studies

• Asbestos dust as a nucleation center in the calcification of old fibrous tissue lesions, and the possible association of this process to the formation of asbestos bodies — J.M. Davis (1970)
• Acute and chronic effects of intraperitoneal injection of two types of asbestos in rats with a study of the histopathogenesis and ultrastructure of resulting mesotheliomas — M.L. Shin, H.I. Firminger (1973)
• The calcification of fibrous pleural lesions produced in guinea-pigs by the injection of chrysotile asbestos dust — J.M. Davis (1971)
• Asbestos body formation and iron accumulation in mouse peritoneal granulomas after the introduction of crocidolite asbestos fibers — H.K. Koerten, J. Hazekamp, et al. (1990)
• Epithelial outgrowths from lung tissue following intrapleural injection of asbestos dust in experimental animals — J.M. Davis (1971)
• Pulmonary response, in vivo, to silicon carbide whiskers — G.L. Vaughan, S.A. Trently, et al. (1993)

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