The effect of different mineral dusts on the mechanism of phagocytosis: a scanning electron microscope study

Our plain-English summary of The effect of different mineral dusts on the mechanism of phagocytosis: a scanning electron microscope study, by K. Miller, R.I. Handfield, E. Kagan (Environmental Research, 1978).

The study

• Authors: K. Miller, R.I. Handfield, E. Kagan
• Journal: Environmental Research
• Published: 1978;15(1):139-54
• Cited by: 22 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Alveolar macrophages from normal rats were incubated with crocidolite asbestos fibers and quartz particles in vitro. The early events in phagocytosis were studied sequentially. Differences were found in the way in which macrophages recognized, attached, and phagocytosed the two dusts. Phagocytosis of quartz was extremely rapid: The macrophages typically developed long tenuous filopodia. Crocidolite was phagocytosed more slowly: Many macrophages developed large flattened pseudopodia. These different phagocytic mechanisms may reflect the different biochemical and cytotoxic properties of the dusts.

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

In plain English

In this test-tube study, dusts were added to rat lung scavenger cells (alveolar macrophages) growing on glass cover slips, not given to living animals or people. The cells came from normal adult male Wistar rats. Each culture received one of five materials: short crocidolite asbestos fibers (5 micrometres or less), long crocidolite fibers (20 micrometres or more), quartz particles, glass fibers, or Staphylococcus aureus bacteria. Samples were taken every 2 minutes for 30 minutes and examined with a scanning electron microscope. Both short and long crocidolite fibers were firmly attached to the cells after 4 minutes. With long fibers, many cells spread large flat extensions and swallowed the fibers end first. One 50-micrometre fiber was too long for any cell to take in, and long fibers were still present after 30 minutes. The cells handled glass fibers in a similar way. Quartz was swallowed within 2 to 4 minutes, and the cells put out long, thin projections. The authors concluded that the two dusts interact differently with macrophage membranes. They said the cause of the difference is not known, and that the study does not explain the different lesions of silicosis and asbestosis.

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) study of cultured rat alveolar macrophages, examined by scanning electron microscopy at intervals after adding dusts
• Who was studied: Alveolar macrophages washed out of the lungs of adult male outbred Wistar rats and grown on glass cover slips in disposable trays. The number of rats was not stated.
• Exposure: Crocidolite asbestos fibers in two samples (fibers 20 µm long or more; fibers 5 µm long or less), quartz particles 1 to 3 µm across, milled glass fibers (5 to 100 µm long) and Staphylococcus aureus bacteria for comparison. Dust was added at 100 µg per ml of culture medium. Samples were taken every 2 minutes for 30 minutes for scanning electron microscopy.
• Main results:
  • Both short and long crocidolite fibers were firmly attached to the macrophages after 4 minutes.
  • With short crocidolite fibers, very few macrophages still had attached fibers after 20 minutes.
  • With long crocidolite fibers, many macrophages developed large flattened pseudopodia (cell extensions) with an elevated central mass.
  • Long crocidolite fibers being swallowed were often coated with cell debris.
  • In one instance a crocidolite fiber 50 µm long was too long to be taken into a macrophage.
  • After 30 minutes, long crocidolite fibers were still present in the cultures.
  • Glass fibers were thicker and shorter than the crocidolite fibers. The cells attached and swallowed them in a way that seemed quite similar.
  • Quartz particles were swallowed extremely rapidly, within 2 to 4 minutes.
  • Macrophages exposed to quartz formed extensive long, thin filopodia (thread-like projections).
  • Staphylococcus aureus bacteria were also swallowed extremely rapidly, and none were found after 4 minutes.
• The authors' conclusion: The authors concluded that quartz and crocidolite interact differently with alveolar macrophage membranes. They suggested that these early events may have some bearing on the macrophage's role in dust diseases.
• Limitations the authors state:
  • The authors said it is not known whether the differences are due to the size and shape of the minerals or to physicochemical interactions.
  • The authors said this in vitro study does not explain the different nature and distribution of lesions in silicosis and asbestosis.

Topics

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

Related studies

• Cytotoxic effects of some mineral dusts on Syrian hamster peritoneal macrophages — E. Bey, J.S. Harington (1971)
• Enhanced generation of free radicals from phagocytes induced by mineral dusts — V. Vallyathan, J.F. Mega, et al. (1992)
• Cytotoxicity of respirable dusts from industrial minerals: comparison of two naturally occurring and two man-made silicates — D. Nadeau, L. Fouquette-Couture, et al. (1987)
• Lung dust content in idiopathic pulmonary fibrosis: a study with scanning electron microscopy and energy dispersive x ray analysis — E. Monsó, J.M. Tura, et al. (1991)
• Antibody producing cells in the spleens of mice treated with pathogenic mineral dust — S. Szymaniec, D.M. Brown, et al. (1989)
• The ability of mineral dusts and fibres to initiate lipid peroxidation. Part I: parameters which determine this ability — M. Gulumian (1999)

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