The effects of chrysotile asbestos dust on lung macrophages maintained in organ culture. An electron-microscope study

Our plain-English summary of The effects of chrysotile asbestos dust on lung macrophages maintained in organ culture. An electron-microscope study, by J.M. Davis (British Journal of Experimental Pathology, 1967).

The study

• Author: J.M. Davis
• Journal: British Journal of Experimental Pathology
• Published: 1967;48(4):379-85
• Cited by: 46 articles, as counted by NIH iCite
• Read it: PubMed · Free full text

Abstract

Chrysotile asbestos dust was injected into small pieces of adult guinea-pig lung maintained in organ culture for 10-14 days. This dust was taken up by the lung macrophages in a matter of hours, but dust was not found in any of the other cells during the course of these experiments. The macrophages in contact with dust produce elongated phagocytic processes on the cell surface and these encircle the dust and fold back onto the cell to form phagocytic vacuoles or phagosomes. The dust may remain in the phagosomes for some time or it can quickly escape into the cytoplasm perhaps by mechanical action. If the dust remains in a phagosome this eventually contracts to form a small dense structure usually called a residual body. In the cultured lung it was found that dust containing macrophages could quickly combine to form giant cells, and quite large specimens were often found within 24 hr. Some macrophages eventually become converted into fibroblasts with asbestos dust still retained in the fibroblast cytoplasm.

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

In plain English

This laboratory study, by a single author at the University of Cambridge, used small pieces of adult guinea-pig lung kept alive in organ culture. Finely milled chrysotile asbestos (about 5 mg per ml, mostly fibres 5 microns or less long) was injected into the tip of each lung piece, which was then tied off. The tissue was examined by light and electron microscopy. The article does not say how many cultures were studied. Only lung macrophages (scavenger cells) took up the dust: some contained it within 30 minutes, and almost all by 2 hours. Some fibres escaped from the cells' digestive sacs into the cell interior, sometimes by puncturing them. Other sacs shrank into dense 'residual bodies'. Dust-containing macrophages fused into large giant cells within 24 hours. Some macrophages later became fibroblasts that still held dust. Dusted cultures often had dead tissue at the centre, which the author linked to the injection distending the pieces beyond the 2 mm through which oxygen can adequately diffuse. The author concluded that the changes previously reported in dusted live guinea-pigs could all be produced in this culture system.

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: Laboratory experiment on animal lung tissue kept in organ culture, examined by light and electron microscopy
• Who was studied: Small pieces of adult guinea-pig lung maintained in organ culture (number of animals or cultures not stated), Department of Pathology, University of Cambridge
• Exposure: Finely milled chrysotile asbestos dust, mainly fibres 5 microns or less long, suspended at about 5 mg per ml and injected into the tip of small lung lobes, which were then tied off with a suture
• Main results:
  • In the cultured guinea-pig lung, dust was inside macrophages within 30 minutes, and almost all macrophages contained dust by 2 hours
  • Dust was not found in any cells other than the macrophages
  • Within 2 hours some dust had escaped from the phagosomes (digestive vacuoles) into the cytoplasm; in some cases long fibres punctured the phagosome wall mechanically
  • Dust-containing 'cytosome' (residual body) structures were absent in the first few days and most common after 3 or 4 days
  • Primary lysosomes in the macrophages became much more common from about 48 hours onwards
  • In some cells ('foamy macrophages') most of the dust stayed in phagosomes for several days
  • Dust-containing macrophages combined into quite large giant cells within 24 hours
  • None of the giant cells contained dust particles longer than 5 microns
  • Some macrophages eventually became fibroblasts that still contained asbestos dust
  • Central necrosis was often found in the dusted cultures, with a band of living tissue about 1 mm thick on the outside
  • Apart from these changes, the lung tissue as a whole seemed unaffected by the dust and could be kept alive for at least 9 days
• The authors' conclusion: The author concluded that the changes previously reported in dusted live guinea-pigs could all be produced in lung pieces in organ culture, making the system useful for further study. The author also concluded that giant cell formation appears to result from foreign material being concentrated in one place, not from its size.
• Limitations the authors state:
  • Injecting the dust distended the lung pieces, making it difficult to keep them within the 2 mm diameter through which oxygen can adequately diffuse; the author gives this as the reason for the central necrosis in dusted cultures
  • The system is less suitable for studying collagen production (fibrosis) caused by asbestos, because fibrosis also occurs in later stages of culture of normal lung tissue
  • The cause of phagosome rupture could not be determined in every case

Topics

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

Medical terms in this study, explained in our Lexicon: Chrysotile, Macrophage, Fibroblast.

Related studies

• Effects of chrysotile and acid-treated chrysotile on macrophage cultures — E.G. Beck, P.F. Holt, et al. (1971)
• Comparison of effects on macrophage cultures of glass fibre, glass powder, and chrysotile asbestos — E.G. Beck, P.F. Holt, et al. (1972)
• An electron microscopy study of the effect of asbestos dust on the lung — J.M. Davis (1963)
• Electron-microscope studies of asbestosis in man and animals — J.M. Davis (1965)
• In vitro biodegradation of chrysotile fibres by alveolar macrophages and mesothelial cells in culture: comparison with a pH effect — M.C. Jaurand, A. Gaudichet, et al. (1984)
• Electron microscope characteristics of inhaled chrysotile asbestos fibre — F.D. Pooley (1972)

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