Cytotoxic effects of some mineral dusts on Syrian hamster peritoneal macrophages

Our plain-English summary of Cytotoxic effects of some mineral dusts on Syrian hamster peritoneal macrophages, by E. Bey, J.S. Harington (The Journal of Experimental Medicine, 1971).

The study

• Authors: E. Bey, J.S. Harington
• Journal: The Journal of Experimental Medicine
• Published: 1971;133(5):1149-69
• Cited by: 60 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Hamster peritoneal macrophages were grown in cell culture and their response to various conditions was examined. The cultures responded favorably to high concentrations of serum and to medium which had been preconditioned by contact with tumor cells. After 2-3 days of adaptation, they entered into a period of stability which lasted from the 4th to the 9th day. Macrophage cultures in this stable phase were treated with various samples of mineral dusts and their response determined by counting the number of viable macrophages/cm(2) at intervals over a period of 72 hr. Crystalline silica Snowit was found to be nontoxic. Amorphous silica Fransil caused a characteristic cytotoxic effect and a rapid decline in cell population at doses less than 150 microg/5 x 10(5) cells. Of the three different kinds of asbestos used, chrysotile was toxic and amosite and crocidolite nontoxic at equivalent concentrations. A comparison of two preparations of chrysotile which differed in surface area showed that weight rather than surface area determines toxicity. Pretreatment of chrysotile with tryptose phosphate broth under drastic conditions accelerated but did not increase the final intensity of the cytotoxic effect.

In plain English

This was a laboratory experiment on cells, not people. The authors grew macrophages (scavenger cells) washed from the abdominal cavity of Syrian hamsters. On day five of culture they exposed them to two forms of silica and three standard UICC asbestos samples (chrysotile, amosite and crocidolite) at effective doses of 36, 72 and 144 micrograms per 5 x 10^5 cells. They counted surviving cells over 72 hours. Chrysotile damaged the cells, more so with higher dose and longer exposure: 72 micrograms had killed 50% of the cells by 36 hours. Amosite and crocidolite showed no specific toxic effect, though some cells were lost after taking up many fibers. The authors called this loss mechanical and said released fibers might pass to other cells and cause delayed damage. Amorphous silica (Fransil) was toxic; crystalline silica (Snowit) was not. Chrysotile with a larger surface area was no more toxic. Boiling chrysotile in broth caused a slight but significant early rise in toxicity, without raising its final intensity. The authors cautioned that cell-culture results must be correlated with events in living animals.

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 experiment
• Who was studied: Peritoneal macrophages from male or female Syrian hamsters about 6 months old, about 5 x 10^5 mature macrophages per dish. Each experiment used cells from a single animal. The total number of animals is not stated. Work done in Johannesburg, South Africa.
• Exposure: Crystalline silica Snowit, amorphous silica Fransil, and standard UICC reference samples of crocidolite, amosite and chrysotile. Each was added as 100, 200 or 400 micrograms per dish, taken as an effective 36% of the amount added: 36, 72 or 144 micrograms per 5 x 10^5 cells. Modified samples were chrysotile and amosite with large fibers removed (higher surface area), and chrysotile and Fransil boiled in tryptose phosphate broth.
• Main results:
  • UICC chrysotile had a specific cytotoxic effect on the hamster macrophages that depended on dose and exposure time. 72 micrograms of fiber killed 50% of the 5 x 10^5 cells per dish by the end of 36 hours.
  • UICC amosite and crocidolite at 36, 72 and 144 micrograms per 5 x 10^5 macrophages did not show significant effects on cell numbers. Some cells were lost over 3 days, which the authors attributed to overingestion of particles rather than a direct toxic effect.
  • Amorphous silica Fransil was toxic within an hour. Half of the macrophages were killed within 18 hours at 72 micrograms and within 12 hours at 144 micrograms per 5 x 10^5 cells.
  • With crystalline silica Snowit, about 90% of the cells remained morphologically intact. The authors reported no cytotoxic effect over 72 hours.
  • Chrysotile with a surface area of 23.54 m2/g and chrysotile with 34.18 m2/g (large fibers removed) did not differ in toxicity. The same was true for two amosite samples of different surface areas.
  • Chrysotile boiled in tryptose phosphate broth showed a slight but significant increase in toxicity in the early stages of the experiments. Its effect appeared earlier, but it was in the end as toxic as freshly prepared chrysotile, with no increase in final intensity. Boiled Fransil silica did not differ from untreated Fransil.
• The authors' conclusion: The authors concluded that, under their experimental conditions, standard amosite and crocidolite and a form of crystalline silica were not obviously toxic to hamster peritoneal macrophages, while chrysotile and a form of amorphous silica were specifically cytotoxic. They suggested the weight of chrysotile given, rather than its surface area, may determine toxicity.
• Limitations the authors state:
  • The authors said the usefulness of this cell-culture method depends on establishing a correlation between events in living animals and in culture.
  • The authors noted that little is known about the effects of mineral dusts in living hamsters, and that silicosis in the hamster is atypical compared with other experimental animals.
  • The authors stated that the surface area of chrysotile fibers cannot be measured accurately.
  • The authors noted that fibers released from macrophages overloaded with amosite or crocidolite could be taken up by other healthy cells and lead to a delayed disruptive effect.

Topics

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

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)
• Some biochemical effects of asbestos on macrophages — K. Miller, J.S. Harington (1972)
• Cytotoxic action of mineral dusts on CHV 79 cells in vitro: factors affecting toxicity — S.O. Lock, M. Chamberlain (1983)
• Polyvinylpyridine-N-oxide and carboxymethyl cellulose inhibit mineral dust-induced production of reactive oxygen species by human macrophages — P. Nyberg (1991)
• Effect of mineral dusts on metabolic cooperation between Chinese hamster V79 cells in vitro — M. Chamberlain (1983)

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