Depression of viral interferon induction in cell monolayers by asbestos fibers

Our plain-English summary of Depression of viral interferon induction in cell monolayers by asbestos fibers, by N. Hahon, H.L. Eckert (Environmental Research, 1976).

The study

• Authors: N. Hahon, H.L. Eckert
• Journal: Environmental Research
• Published: 1976;11(1):52-65
• Cited by: 31 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Studies on the induction of interferon by influenza virus revealed that this adaptive cellular response was depressed, completely or partially, in either amosite, crocidolite, anthophyllite, Canadian or Rhodesian chrysotile-treated monkey kidney (LLC-MK2) cell monolayers. Asbestos fiber concentrations of 1 mg/1.0 × 10^7 cells, which minimally affected cell viability, depressed interferon production by almost 90%. Increases in the virus-cell multiplicity of infection did not significantly increase interferon yields in asbestos fiber-treated cells. Chrysotile B fibers of lengths ranging from 10 to 5 µm were more effective in reducing interferon yields than those ranging from 75 to 625 µm. Maximal depression of interferon production was dependent on prior treatment of cell monolayers with asbestos fibers before the addition of viral inducer. The processes of virus integration (attachment and penetration) into and virus multiplication in cells were unaffected by the presence of asbestos fibers, however, a slightly higher level of virus replication was noted in asbestos fiber-treated cells. When cells were primed with interferon, the presence of asbestos fibers did not interfere with the ability of the primer to enhance interferon production. Neither interferon antagonists, interference with virus-cell interactions, nor adsorption by asbestos fibers accounted for the depression of interferon yields. These findings suggest that asbestos fibers act on cell membranes in a manner, as yet undetermined, to interpose in the viral inductive process of interferon synthesis.

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

In plain English

This was a laboratory study in cell cultures, not a study of people. The authors grew rhesus monkey kidney cells (LLC-MK2) and exposed them to standard UICC samples of amosite, anthophyllite, crocidolite, Canadian chrysotile, Rhodesian chrysotile and chrysotile B. They then added ultraviolet-treated influenza virus, which normally prompts cells to make interferon, one of the body's defences against viruses. At 1 mg per 10 million cells, a dose with no significant toxic effect on the cells, each of the five fiber types other than chrysotile B depressed interferon production by almost 90%. At 0.01 mg, all of these five except amosite still partly depressed it. At the higher dose tested, shorter chrysotile B fibers (10 to 50 micrometres) cut interferon more than longer ones (75 to 625 micrometres). The fibers worked best when added before the virus. They did not stop the virus from attaching to or entering cells. They did not bind interferon, and no blocking substance was found. The authors concluded that the depression was attributable to the asbestos fibers themselves. They said the mechanism is not precisely known.

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 experiments
• Who was studied: No human or animal subjects. Rhesus monkey kidney cells (LLC-MK2) were used to produce interferon, and human Chang conjunctiva cells were used to measure it. Both cell lines came from the American Type Culture Collection. The work was done at the U.S. Public Health Service Appalachian Laboratory for Occupational Respiratory Diseases and West Virginia University, Morgantown. The article was received in May 1975.
• Exposure: Six asbestos samples were tested on the cells:
• UICC standard samples of amosite, anthophyllite, crocidolite, Canadian chrysotile and Rhodesian chrysotile. 96 to 98% of these fibers were 30 micrometres or shorter.
• UICC chrysotile B, with fibers 75 to 625 micrometres long.

The fibers were added to the flasks of cells in amounts of up to 10 mg. Usually 1 mg per 10 million cells or less was used.

• Main results:
  • Cell survival after 24 hours was reduced by all six asbestos samples at 10 mg. Rhodesian chrysotile was generally the most harmful to the cells.
  • At 1 mg per 10 million cells, none of the six asbestos samples had a significant toxic effect on the cells.
  • At 1.0 mg, interferon production fell by almost 90% for all five fiber types in Table 2: amosite, anthophyllite, crocidolite, Canadian chrysotile and Rhodesian chrysotile. The article's abstract gives this dose as 1 mg per 10 million cells. Interferon titer was 50 in fiber-treated cells, compared with 380 in untreated control cells. Chrysotile B was not in this test.
  • At 0.01 mg, all fiber types in Table 2 except amosite still partly reduced interferon production. These were anthophyllite, crocidolite, Canadian chrysotile and Rhodesian chrysotile.
  • In amosite-treated cells, adding more virus did not markedly raise interferon production. In untreated cells, interferon appeared to double with each tenfold increase in virus.
  • Short chrysotile B fibers (10 to 50 micrometres) reduced interferon more than long fibers (75 to 625 micrometres) at the higher dose. The untreated control titer was 700.
• At 2 mg: short fibers gave a titer of 130 (81.5% reduction); long fibers gave 340 (51.5% reduction).
• At 0.2 mg: short fibers gave 310 (55.8% reduction); long fibers gave 350 (50.0% reduction).
  • Treating cells with asbestos as little as 2 hours before adding the virus cut interferon production by 50% to about 90%, depending on the amount of asbestos.
  • In the authors' summary, fibers added at the same time as, or after, the virus did not significantly affect interferon production. The Results section adds that when fibers and virus were added together, only the higher amounts of asbestos inhibited interferon.
  • Amosite did not hinder the influenza virus from attaching to the cells or entering them.
  • In anthophyllite-treated cells, the virus grew at a similar rate but reached a slightly higher (twofold) level than in untreated cells. Only minimal interferon (less than one unit) was detected in the anthophyllite-treated cells over 48 hours.
  • Pretreating cells with a small amount of interferon ('priming') still raised interferon production in anthophyllite-treated cells (a threefold increase), as it did in untreated cells.
  • Fluid taken from asbestos suspensions did not depress interferon production; the resuspended fibers did.
  • Interferon did not stick to the fibers. Amosite, Canadian chrysotile, crocidolite and anthophyllite were tested.
  • Fluid from asbestos-treated cells contained no substance that worked against interferon.
• The authors' conclusion: The authors concluded that the depression of interferon production in the cell cultures was attributable to the asbestos fibers themselves.
• Limitations the authors state:
  • Tests of whether fiber length matters could only be done with chrysotile B.
  • How the fibers act on cells to reduce interferon production is not known.

Topics

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

Related studies

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• Induction of interferon in human subjects by poly I:C — A.K. Field, C.W. Young, et al. (1971)
• Chemotherapy delivered after viral immunogene therapy augments antitumor efficacy via multiple immune-mediated mechanisms — Z.G. Fridlender, J. Sun, et al. (2010)
• Mitotic disturbances and micronucleus induction in Syrian hamster embryo fibroblast cells caused by asbestos fibers — E. Dopp, J. Saedler, et al. (1995)
• Induction of heme oxygenase in mammalian cells by mineral fibers: distinctive effect of reactive oxygen species — K. Suzuki, T.K. Hei (1996)
• Induction of metaphase and anaphase/telophase abnormalities by asbestos fibers in rat pleural mesothelial cells in vitro — M. Yegles, L. Saint-Etienne, et al. (1993)

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