Interactions of asbestos-activated macrophages with an experimental fibrosarcoma

Our plain-English summary of Interactions of asbestos-activated macrophages with an experimental fibrosarcoma, by K. Donaldson, J.M. Davis, A. Ewing, et al (Environmental Health Perspectives, 1983).

The study

• Authors: K. Donaldson, J.M. Davis, A. Ewing, K. James
• Journal: Environmental Health Perspectives
• Published: 1983;51:97-101
• Cited by: 2 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Supernatants from in vivo asbestos-activated macrophages failed to show any cytostatic activity against a syngeneic fibrosarcoma cell line in vitro. UICC chrysotile-induced peritoneal exudate cells also failed to demonstrate any growth inhibitory effect on the same cells in Winn assays of tumor growth. Mixing UICC crocidolite with inoculated tumor cells resulted in a dose-dependent inhibition of tumor growth; this could, however, be explained by a direct cytostatic effect on the tumor cells of high doses of crocidolite, which was observed in vitro.

In plain English

This was a laboratory and mouse study of whether asbestos-activated macrophages (immune cells) could slow the growth of a mouse tumor cell line, the CCH1 fibrosarcoma. The authors injected UICC crocidolite, UICC chrysotile, latex spheres or saline into the peritoneal (abdominal) cavity of mice and collected the cells that gathered there three days later. Compared with saline-induced macrophages, chrysotile-induced macrophages had less of one enzyme and more of another. Fluid from cultures of these macrophages had no statistically significant effect on tumor cell growth in the dish. When chrysotile-induced cells were mixed with tumor cells and injected under the skin of groups of 10 mice, differences in tumor size were not statistically significant. Mixing crocidolite itself into the tumor injection reduced tumor growth in a dose-dependent way. In the dish, however, the highest crocidolite doses directly inhibited the tumor cells. The authors concluded that the reduction in tumor size could be accounted for by direct toxic effects of crocidolite on the tumor cells. They wrote that their results suggested asbestos-activated macrophages had not reached the fully tumor-killing state.

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 combined with laboratory (cell culture) experiments
• Who was studied: Mice (groups of 10 for the tumor growth experiments) and the CCH1 fibrosarcoma cell line, which was derived from a methylcholanthrene-induced tumor in CBA/Ca mice. The work came from the Institute of Occupational Medicine and the University of Edinburgh, Scotland. Dates are not given.
• Exposure: Intraperitoneal injection of UICC crocidolite, UICC chrysotile (5 mg in the Winn assay), latex spheres or saline, used to produce peritoneal macrophages. Crocidolite was also mixed directly into the tumor cell inoculum at 0, 5, 50 or 500 micrograms. Crocidolite, chrysotile and their fluid leachates were also added to tumor cells in culture.
• Main results:
  • Chrysotile-induced macrophages had lower plasma membrane 5'-nucleotidase (0.5 versus 3.7 for saline-induced macrophages) and higher acid phosphatase (4.7 versus 0.4), measured as phosphate released per mg protein per hour.
  • Supernatants from saline-, latex-, crocidolite- or chrysotile-induced macrophages had no statistically significant effect on CCH1 tumor cell proliferation in vitro. This was the mean of five separate experiments, with considerable variation.
  • In Winn assays at cell ratios of 10:1 and 100:1, the authors compared mean tumor diameter for tumor cells alone, tumor cells with saline-induced cells and tumor cells with chrysotile-induced cells. The differences were not statistically significant.
  • Crocidolite preincubated with normal mouse serum and mixed into the tumor cell inoculum produced a dose-dependent inhibition of tumor growth in mice.
  • In vitro, crocidolite and chrysotile had little effect on tumor cell proliferation except at the very highest doses, where crocidolite caused marked inhibition. Crocidolite leachate at the highest concentration also caused inhibition.
• The authors' conclusion: The authors concluded that the reduction in tumor size from crocidolite in the inoculum could be accounted for by direct toxic effects of crocidolite on the tumor cells, so macrophage action need not be invoked. They also wrote that the results suggest asbestos-activated macrophages have not attained the fully activated tumoricidal (tumor-killing) state.
• Limitations the authors state:
  • No positive cytostatic (growth-inhibiting) control was included in the Winn assay experiments.
  • The response of tumor cells to macrophage supernatants varied considerably between experiments.

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, UICC, Chrysotile, Exudate, Crocidolite.

Related studies

• Cytotoxic effect of asbestos on macrophages in different activation states — A. Wright, K. Donaldson, et al. (1983)
• Asbestos-activated peritoneal macrophages release a factor(s) which inhibits lymphocyte mitogenesis — K. Donaldson, J.M. Davis, et al. (1984)
• The mechanism of pleural inflammation by long carbon nanotubes: interaction of long fibres with macrophages stimulates them to amplify pro-inflammatory responses in mesothelial cells — F.A. Murphy, A. Schinwald, et al. (2012)
• Secretion of fibronectin by mineral dust-derived alveolar macrophages and activated peritoneal macrophages — R. Davies, G. Erdogdu (1989)
• Activated alveolar macrophages express the insulin-like growth factor-I receptor — W.N. Rom, P. Pääkkö (1991)
• Some biochemical effects of asbestos on macrophages — K. Miller, J.S. Harington (1972)

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