Transport of inhaled dust to extrapulmonary sites

Our plain-English summary of Transport of inhaled dust to extrapulmonary sites, by P.F. Holt (The Journal of Pathology, 1981).

The study

• Author: P.F. Holt
• Journal: The Journal of Pathology
• Published: 1981;133(2):123-9
• Cited by: 27 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

A histological study of the lungs of guinea-pigs that inhaled carbon, chrysotile asbestos or crocidolite asbestos dust indicated that dust particles in macrophages move through alveolar walls towards the pleura. After some weeks accumulations of dust-filled macrophages were found near to pulmonary blood vessels. Macrophages that ingested carbon appeared to be much less mobile than those that ingested carbon appeared to be such less mobile than those that ingested asbestos. In sections from the animals that inhaled asbestos, macrophages were found that were penetrating the wall of blood vessels, dust is transferred to extrapulmonary sites by macrophages in the blood

In plain English

The author cut lung sections from wax blocks kept from earlier experiments on guinea-pigs that had inhaled submicron carbon, chrysotile asbestos or crocidolite asbestos dust (for 24 or 100 hours, according to the figure legends) and were killed a few days to 72 weeks later. The aim was to see whether dust inside macrophages, a type of scavenger cell, leaves the lung through blood vessels. The number of animals was not given. With chrysotile, macrophages reacted strongly to Perls' stain 3 or 4 weeks after exposure. Several were seen passing through blood vessel walls, one carrying two long asbestos fibres; occasionally an asbestos body appeared inside a vessel. Crocidolite sections looked similar. Carbon was taken up slowly. A few clusters of carbon-laden macrophages near blood vessels appeared in animals killed after 72 weeks; these macrophages seemed much less mobile than asbestos-laden ones. The author concluded that inhaled dust may reach organs outside the lung through the blood, and that asbestos bodies found elsewhere were probably formed in the lung. The author noted that electron microscopy of these cells was desirable but that preparing a suitable specimen was impracticable.

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: histological examination of new sections cut from wax blocks kept from earlier dust-inhalation experiments
• Who was studied: Specific pathogen free guinea-pigs. The number of animals, place and dates of the original experiments were not stated (the author was at the Department of Chemistry, University of Reading).
• Exposure: Inhaled submicron carbon dust (from carbon fibre, almost entirely nonfibrous), chrysotile asbestos dust or crocidolite asbestos dust. Figure legends give inhalation times of 24 hr (chrysotile, crocidolite) or 100 hr (carbon, crocidolite), with animals killed up to 72 weeks later.
• Main results:
  • Chrysotile group: macrophages gave a strong Perls-positive reaction 3 or 4 weeks after inhalation
  • Chrysotile group: several macrophages were seen passing through the walls of blood vessels
  • Chrysotile group: in one section a macrophage inside a blood vessel carried two long Perls-positive asbestos fibres through the vessel wall
  • Chrysotile group: occasionally a Perls-positive macrophage or an asbestos body was seen inside a blood vessel
  • Crocidolite group: sections resembled those from the chrysotile group
  • Carbon group: little dust was inside cells after 6 weeks
  • Carbon group: a few accumulations of dust-bearing macrophages near blood vessels and bronchioles were seen in animals killed after 72 weeks
  • Carbon-laden macrophages appeared much less mobile than asbestos-laden macrophages
• The authors' conclusion: The author concluded that inhaled dust particles may reach organs outside the lung directly through the blood, and that asbestos bodies found away from the lung were probably formed in the lung and carried in the blood.
• Limitations the authors state:
  • The author considered electron microscopic study of these cells desirable but found that preparing a suitable specimen was impracticable.

Topics

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

Related studies

• Translocation of inhaled dust to the pleura — P.F. Holt (1983)
• An assessment of asbestos body formation in extrapulmonary sites: liver and spleen — M.G. Williams, R.F. Dodson, et al. (2001)
• Kinetics of deposition and clearance of inhaled mineral dusts during chronic exposure — J.H. Vincent, A.M. Johnston, et al. (1985)
• In vitro cytotoxicity and transforming potential of industrial carbon dust (fibers and particles) in syrian hamster embryo (SHE) cells — C. Darne, F. Terzetti, et al. (2010)
• An electron microscopy study of the effect of asbestos dust on the lung — J.M. Davis (1963)
• Biochemical changes and pulmonary response of guinea pigs to asbestos dust — J. Singh, M.U. Beg, et al. (1976)

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