An ultrastructural study of the effects of asbestos fibres on cultured peritoneal macrophages

Our plain-English summary of An ultrastructural study of the effects of asbestos fibres on cultured peritoneal macrophages, by N.F. Johnson, R. Davies (British Journal of Experimental Pathology, 1981).

The study

• Authors: N.F. Johnson, R. Davies
• Journal: British Journal of Experimental Pathology
• Published: 1981;62(6):559-70
• Cited by: 8 articles, as counted by NIH iCite
• Read it: PubMed · Free full text

Abstract

The effects of crocidolite and chrysotile fibres on lavaged peritoneal macrophages have been studied by both scanning (SEM) and transmission (TEM) electron microscopy. SEM provided little information (as the surface topography did not reflect the underlying cytoplasmic organization) except that it showed that individual macrophages often partially engulfed many long fibres in a random fashion. TEM revealed the fibres in and protruding from membrane-bound vacuoles, free in the cytoplasm and penetrating the nucleus. The cellular distribution of the fibres is discussed in terms of the cytotoxic nature of the fibres and their ability to produce a selective release of enzymes from the macrophages.

In plain English

This laboratory study used electron microscopes to examine how asbestos fibres interact with macrophages, a type of scavenger cell. The authors collected macrophages by washing out the abdominal (peritoneal) cavity of female mice and grew them in culture. They exposed the cells for 18 hours to UICC crocidolite, UICC chrysotile B or magnetite dust, with undusted controls. Scanning microscopy, which shows cell surfaces, found that most macrophages had partly taken in several fibres at random, and that several cells were often associated with one long fibre. Transmission microscopy, which shows cell interiors, found asbestos fibres inside membrane-bound sacs, sticking out of them and loose in the cell. Fibres inside the nucleus were seen only with chrysotile. Magnetite particles lay next to the cell surface and inside membrane-bound sacs. Asbestos-exposed cultures also contained dead cells. The authors concluded that surface scanning was of little use for judging cell changes. They suggested fibre damage to cells may partly come from the fibres' shape and rigidity. They noted that damaged crocidolite and magnetite sections may have made their observations selective.

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 (in vitro) cell-culture study using scanning and transmission electron microscopy
• Who was studied: Unstimulated peritoneal macrophages obtained by lavage from 22-27 g female T.O. mice, grown in culture at the MRC Pneumoconiosis Unit, Penarth, Wales. The number of mice or cultures is not stated.
• Exposure: UICC crocidolite, UICC chrysotile B or magnetite (BDH), each added at 60 µg/ml for 18 h. The unit is garbled in the scanned text and appears to be micrograms per millilitre. Undusted cultures served as controls.
• Main results:
  • By scanning microscopy, most macrophages exposed to chrysotile or crocidolite had partially ingested several fibres in a random way.
  • Several macrophages were often associated with a single long fibre.
  • Many more fibres were present in the chrysotile cultures than in the crocidolite cultures.
  • Asbestos-exposed cultures contained dead cells, often with fibres passing through the cell remnants.
  • In crocidolite cultures the cells were frequently clumped together; this was not marked with chrysotile.
  • With all 3 dusts, stellate (star-shaped) cells appeared to be fewer than in undusted cultures.
  • By transmission microscopy, chrysotile and crocidolite fibres were found in membrane-bound vesicles and vacuoles. They were also found free in the cytoplasm, protruding from lysosomes and vacuoles, and within the nucleus.
  • Fibres inside the nucleus were found only in chrysotile-exposed cultures.
  • In many asbestos-exposed cells the nucleus was deformed by nearby vacuoles or fibres.
  • Long fibres were partially engulfed in deep invaginations of the cell surface that were not sealed off from the outside of the cell.
  • Most dusted cells looked similar inside to control cells, except that the Golgi apparatus was often better developed and there were occasional focal areas of cell lysis.
• The authors' conclusion: The authors concluded that scanning microscopy was of little use for evaluating cell changes, although it did show partial fibre ingestion. They suggested that the cytotoxic effect of fibres may be due in part to the fibres' shape and rigidity, for example by penetrating structures such as the nucleus and lysosomes. They also proposed that incomplete closure of the cell membrane around partly ingested fibres could allow enzymes to be released.
• Limitations the authors state:
  • Crocidolite, and to a lesser extent magnetite, particles often tore the sections during cutting. Observations came from little-damaged sections, which the authors say may have made the crocidolite and magnetite results selective.
  • Scanning electron microscopy was of little use for evaluating cell changes, because surface appearance did not reflect the inside of the cells.
  • The number of coated vesicles in dusted and undusted cultures was not analysed in detail.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Chrysotile, Crocidolite.

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

Related studies

• Reaction of cells cultured in vitro to different asbestos dusts of equal surface area but different fibre length — J.L. Kaw, F. Tilkes, et al. (1982)
• Effects of chrysotile on a lysosomal enzyme preparation and on the hydrolytic enzyme activity of cultured alveolar macrophages — R. Desai, R.J. Richards (1983)
• Effect of asbestos on the P388D1 macrophagelike cell line: preliminary ultrastructural observations — N.F. Johnson, R. Davies (1983)
• 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)
• Cytotoxic effect of asbestos on macrophages in different activation states — A. Wright, K. Donaldson, et al. (1983)
• Comparison of phagocytosis of uncoated versus coated asbestos fibers by cultured human pulmonary alveolar macrophages — T.L. McLemore, V. Roggli, et al. (1981)

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