Stimulation of alveolar macrophages by mineral dusts in vitro: luminol-dependent chemiluminescence study

Our plain-English summary of Stimulation of alveolar macrophages by mineral dusts in vitro: luminol-dependent chemiluminescence study, by V. Vilím, J. Wilhelm, P. Brzák, et al (Environmental Research, 1987).

The study

• Authors: V. Vilím, J. Wilhelm, P. Brzák, J. Hurych
• Journal: Environmental Research
• Published: 1987;42(1):246-56
• Cited by: 16 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Luminol-dependent chemiluminescence (CL) of normal (nonactivated) rabbit alveolar macrophages (AMs) was measured in suspension upon stimulation by various size fractions of one quartz dust sample or by various mineral dusts (quartz, corundum, anatas, and chrysotile asbestos as an example of fibrous dust). The CL-triggering capacity of the tested dusts was inhibited by their preincubation with autologous serum. The intensity of luminol-dependent CL induced by particulate dusts upon their action on AMs depended on the kind of dust, on the dust particle sizes, and on the ratio of the number of particles to the number of cells in a given suspension. The cytotoxicity and/or fibrogenicity of the dust and its capacity to trigger the luminol-dependent CL of nonadherent AMs were not directly correlated.

In plain English

This was a laboratory (in vitro) experiment. The authors used alveolar macrophages, immune cells from the lung's air sacs, washed from healthy rabbits' lungs. They measured a light signal (luminol-dependent chemiluminescence), a widely used way to detect reactive oxygen production by such cells, after adding mineral dusts. They tested size fractions of one quartz dust, two other quartz samples, corundum, titanium dioxide (anatas), and chrysotile asbestos as an example of a fibrous dust. The response depended on the kind of dust, the particle size, and the ratio of particles to cells. Chrysotile asbestos gave a maximum response comparable to the smaller-than-5-micrometre quartz samples, but at a weight dose about one order of magnitude lower. Anatas gave the strongest response of all. Corundum, which the authors call inert, responded almost the same as quartz of similar size. Serum and lung-wash fluid inhibited the response. The authors concluded that this response probably does not play a significant role in the living body. They also concluded that a dust's toxicity to cells or ability to cause fibrosis did not directly correlate with the test result.

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: In vitro laboratory experiment on rabbit alveolar macrophages kept in suspension
• Who was studied: Alveolar macrophages obtained by lung lavage from healthy rabbits (more than 99% of lavaged cells were macrophages); typically 1 x 10^6 cells per test suspension; number of rabbits not stated
• Exposure: Quartz dusts from Svedlár (SQ, several size fractions from under 2 to over 20 micrometres), Dörentrup (DQ) and Lyuberetz (LQ); corundum; titanium dioxide with the anatas structure; and chrysotile asbestos from the Czechoslovak locality of Templštejn. Doses were in the milligram range, for example 0.5 mg added to 1 x 10^6 cells.
• Main results:
  • No cell damage was found (by lactate dehydrogenase release) after 10 minutes of incubation with the dusts.
  • Repeated doses of the same quartz dust (SQ under 5 micrometres) gave progressively lower responses. For example, a second 0.5 mg dose gave a peak area of 72.9 relative units, 45.8% of the first (159.1).
  • Serum inhibited the response, including after quartz, titanium dioxide or asbestos dusts were preincubated with serum. Unprocessed lung-wash supernatant inhibited it by 46% at a 20% concentration and by 85% at a 40% concentration.
  • For quartz fractions under 5 micrometres (SQ and DQ), the maximum response in 1 x 10^6 cells was close to 19 relative units. For fractions under 2 micrometres it was about 6 (SQ) and 4 (DQ) relative units. Larger particles gave higher maximum responses, but required larger weight doses to reach them.
  • Chrysotile asbestos gave a maximum response comparable with the SQ and DQ under-5-micrometre quartz dusts, but at a weight dose approximately one order of magnitude lower. The authors noted that asbestos, being fibrous, cannot be directly compared with particulate dusts.
  • Corundum gave almost the same response as DQ quartz under 2 micrometres. LQ quartz had an optimum of about 50 particles per cell, with a response nearly twice that of the DQ and SQ under-5-micrometre dusts.
  • Anatas (titanium dioxide) had an exceptionally high optimum particle-to-cell ratio of about 500 to 1 and the highest response of all dusts tested.
• The authors' conclusion: The authors concluded that the response depended on dust type, particle size and the particle-to-cell ratio. They judged that reactive oxygen production measured by this short-term test probably does not play a significant role in the living body, because it is inhibited by lung-wash and serum proteins. They found that a dust's cytotoxicity and/or fibrogenicity was not directly correlated with its ability to trigger the response, since strong responses occurred with both cytotoxic and inert dusts.
• Limitations the authors state:
  • The absolute response varied between macrophage preparations, probably depending on the animals' immunological status, and declined with time after isolation, so results were given only in relative units.
  • Very high cell or dust concentrations interfered with the measurement by increasing optical density, which shifted the estimated optimum ratio.
  • The test covers only a very early phase of dust-cell contact; the measurement interval is too short for the cells to complete engulfing the particles.

Topics

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

Related studies

• Secretion of fibronectin by mineral dust-derived alveolar macrophages and activated peritoneal macrophages — R. Davies, G. Erdogdu (1989)
• Interleukin 1 production and accessory cell function of rat alveolar macrophages exposed to mineral dust particles — Y. Oghiso, Y. Kubota (1987)
• Role of extracellular calcium in chrysotile asbestos stimulation of alveolar macrophages — B. Kalla, R.F. Hamilton, et al. (1990)
• The ability of inflammatory bronchoalveolar leucocyte populations elicited with microbes or mineral dust to injure alveolar epithelial cells and degrade extracellular matrix in vitro — K. Donaldson, J. Slight, et al. (1988)
• Stimulation of oxidant production in alveolar macrophages by pollutant and latex particles — G.E. Hatch, D.E. Gardner, et al. (1980)
• In vitro assays to predict the pathogenicity of mineral fibers — B.T. Mossman, A.M. Sesko (1990)

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