In vitro depression of human lymphocyte mitogen response (phytohaemagglutinin) by asbestos fibres

Our plain-English summary of In vitro depression of human lymphocyte mitogen response (phytohaemagglutinin) by asbestos fibres, by R.G. Barbers, W.W. Shih, A. Saxon (Clinical and Experimental Immunology, 1982).

The study

• Authors: R.G. Barbers, W.W. Shih, A. Saxon
• Journal: Clinical and Experimental Immunology
• Published: 1982;48(3):602-10
• Cited by: 13 articles, as counted by NIH iCite
• Read it: PubMed · Free full text

Abstract

Asbestosis is a fibrotic lung disease associated with chronic inhalation of asbestos dust. The response of peripheral blood mononuclear cells (PBM) to phytohaemagglutinin (PHA) in asbestosis patients has been reported to be impaired, suggesting a disturbance in the cell-mediated response of chronically exposed individuals. We demonstrated that PHA responses of normal PBM are also depressed when exposed to various forms of asbestos fibres in vitro. Furthermore, we showed the primary effect of the fibres to be on lymphoid (non-adherent) populations rather than monocytes (adherent cells). Exposure as brief as 1 hr affected the subsequent PHA response of the cells. This effect did not appear to involve suppressor cell activation nor was it mediated by soluble factors. Our findings therefore offer an explanation for the alterations in the cellular immune response observed in humans as a result of lymphoid cells coming into transient contact with inhaled asbestos fibres residing in the lung.

In plain English

This laboratory study tested whether asbestos fibres change how human white blood cells respond to phytohaemagglutinin (PHA), which makes lymphocytes multiply. Cells came from 18 healthy blood donors (8 men, 10 women, aged 24 to 40). Cells were cultured with standard reference amosite, Rhodesian chrysotile or crocidolite, or glass wool as a control fibre. All three asbestos types strongly suppressed the PHA response, while glass wool showed no change in that experiment. Chrysotile had the strongest effect overall, though amosite had a greater effect in one subject. The effect acted on the lymphocyte-rich cell group, not the monocyte-rich group. Chrysotile exposure of just 1 hour reduced the response; 1-hour amosite exposure did not. In cultures with 0.1 mg of fibres per 2 x 10^5 cells, over 80% of cells stayed alive for up to 4 days; where fibres stayed in cultures throughout, more than 0.1 mg was not used because it harmed cell survival. Fluid from fibre-treated cultures did not suppress fresh cells. The authors concluded the findings offer an explanation for immune changes seen in asbestos-exposed people. They noted exposures under 1 hour were not examined.

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 human blood cells
• Who was studied: Blood cells (peripheral blood mononuclear cells) from 18 healthy donors, 8 men and 10 women, mean age 29 (range 24 to 40), UCLA School of Medicine, Los Angeles
• Exposure: UICC standard reference fibres: amosite, Rhodesian chrysotile and crocidolite, added to cell cultures at various concentrations, either for the whole culture period or as a pre-treatment of 1 or 24 hours; sonicated pyrex glass wool as control fibre
• Main results:
  • With fibres present for the whole culture period, amosite, crocidolite and chrysotile all suppressed the PHA response of blood cells; glass wool showed no change
  • Chrysotile had the most pronounced depressive effect of the three asbestos fibres, although amosite had a greater effect in one subject
  • In six experiments with fibres present for the whole culture period, glass wool caused a mean depression of 8.3% (standard deviation 19.9%) and crocidolite 49.7%; the printed figures for amosite and chrysotile are damaged by scanning
  • The depressed response with asbestos was seen throughout 3 to 7 days of culture, and the peak response still came at 4 to 5 days, so the depression was not a shift in timing
  • Pre-exposing the non-adherent (mostly lymphocyte) cells to asbestos depressed the PHA response; pre-treating the adherent (mostly monocyte) cells did not
  • Chrysotile exposure as brief as 1 hour significantly reduced the response; 1-hour amosite exposure had no effect. After 24 hours both chrysotile and amosite depressed the response, but glass wool also caused a depression in that experiment
  • In the viability test, adherent and non-adherent cells were incubated with 0.1 mg of fibres per 2 x 10^5 cells; more than 80% viability was found in all cultures for up to 4 days
  • In the experiments where fibres stayed in the cultures for the whole period, fibre concentrations above 0.1 mg were not used because they were toxic to the cells (data not shown); separate pre-treatment experiments used 1 mg of fibres per 2 x 10^6 cells for 24 hours
  • Fluid (supernatant) from fibre-treated cultures did not suppress fresh cells, and fibre-treated cells did not suppress untreated cells
  • Electron microscopy showed no fibres carried over into the cell fraction after separation
• The authors' conclusion: The authors concluded that their findings offer an explanation for the changes in cellular immune response seen in people, through lymphocytes coming into brief contact with inhaled asbestos fibres in the lung
• Limitations the authors state:
  • Exposure periods shorter than 1 hour were not examined because of the experimental design
  • Subgroups of the cell populations were not examined, so selective killing of particular cell types could not be ruled out directly (the authors considered it unlikely)

Related studies

• Effects of chrysotile asbestos on mononuclear cells in vitro — S. Kagamimori, M.P. Scott, et al. (1980)
• Aryl hydrocarbon hydroxylase induction in mitogen-stimulated lymphocytes by benzanthracene or cigarette tars adsorbed to asbestos fibers — T.L. McLemore, W.T. Jenkins, et al. (1979)
• Lymphocyte responses to phytohaemagglutinin in patients with asbestosis and pleural mesothelioma — P.L. Haslam, A. Lukoszek, et al. (1978)
• Biological effects of asbestos fibers on human cells in vitro--especially on lymphocytes and neutrophils — A. Ueki (2001)
• Chromosomal aberrations induced by chrysotile and crocidolite in human lymphocytes in vitro — F. Valerio, M. de Ferrari, et al. (1983)
• Prognostic significance of the lymphocyte-to-monocyte ratio in patients with malignant pleural mesothelioma — T. Yamagishi, N. Fujimoto, et al. (2015)

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