Chemotactic factor generation by asbestos. Fibre type differences and the effects of leaching

Our plain-English summary of Chemotactic factor generation by asbestos. Fibre type differences and the effects of leaching, by E. Yano, A. Takeuch, Y. Yukiyamo, et al (British Journal of Experimental Pathology, 1984).

The study

• Authors: E. Yano, A. Takeuch, Y. Yukiyamo, R.C. Brown
• Journal: British Journal of Experimental Pathology
• Published: 1984;65(2):223-9
• Cited by: 14 articles, as counted by NIH iCite
• Read it: PubMed · Free full text

Abstract

The generation of chemotactic factors in normal human serum by treatment with chrysotile and crocidolite asbestos was investigated using the Boyden chamber method. Both types of asbestos produced chemotactic activity but not to the same extent. The two fibre types also produced different levels of complement activation as measured by C3 conversion using two dimensional immunoelectrophoresis. While there was a simple correlation between fibre concentration and C3 conversion the production of chemotactic activity declined at high doses of chrysotile. Phosphate buffer treatment reduced the differences between fibre types. The possible role of these phenomena in asbestos-associated disease is discussed.

In plain English

This was a laboratory experiment, not a study of people. The authors mixed two standard reference asbestos samples, UICC chrysotile B and crocidolite, with normal human serum. Using a Boyden chamber, they measured whether the treated serum attracted white blood cells (neutrophils) taken from healthy adults. They also measured activation of complement, part of the immune system, through conversion of a protein called C3. Chrysotile at 1 to 1000 micrograms per ml produced a stronger response than the standard positive control, a bacterial endotoxin. Above 1000 micrograms per ml that response dropped steeply. Crocidolite reached the positive-control level only at 6 mg/ml, the highest concentration practicable. C3 conversion rose with chrysotile concentration and did not drop at high doses. With crocidolite, no conversion was seen below 3 mg/ml. After the fibres were soaked for 24 hours in phosphate buffer, the two types no longer differed significantly below 1 mg/ml. The authors suggested that such changes might help explain some differences between fibre types, but said the role of these processes in asbestosis remains speculation.

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) experiment measuring chemotactic factor generation in serum with the Boyden chamber method, plus complement (C3) conversion by two-dimensional immunoelectrophoresis
• Who was studied: No human or animal subjects. The experiments used normal human serum and neutrophils (polymorphonuclear leucocytes) isolated from blood of healthy adults. The number of donors is not given.
• Exposure: UICC standard reference samples of chrysotile B and crocidolite, autoclaved and added directly to serum at concentrations from about 1 microgram per ml up to 6 mg/ml. Some samples were first leached by shaking at 1 mg/ml in phosphate-buffered saline for 24 hours.
• Main results:
  • Chrysotile at 1 to 1000 micrograms per ml produced greater chemotactic activity than the LPS positive control (defined as a chemotactic index of 100).
  • At chrysotile concentrations above 1000 micrograms per ml, chemotactic activity dropped steeply.
  • Crocidolite reached the activity of the positive control only at 6 mg/ml, the maximum concentration practicable.
  • At 1 to 1000 micrograms per ml, chrysotile was always more active than crocidolite in generating chemotactic activity.
  • C3 conversion increased with chrysotile concentration. The proportion of converted C3 was 0, 11, 27 and 39% at chrysotile concentrations of 0, 200, 3000 and 6000 micrograms per ml.
  • Unlike chemotactic activity, complement activation did not drop at higher chrysotile concentrations.
  • There was no evidence of complement activation with crocidolite below 3 mg/ml. At each concentration tested, conversion was lower for crocidolite than for chrysotile.
  • After leaching, there was no significant difference between the two fibre types at concentrations below 1 mg/ml.
  • Leaching reduced chrysotile's activity at low concentrations. A decline at high chrysotile concentrations remained, but was smaller than with untreated fibre.
  • Leaching consistently increased crocidolite's ability to generate chemotactic activity, which was significant at the 5% level by Student's t-test.
• The authors' conclusion: The authors reported fibre-type differences and leaching effects for the first time. They suggested that the convergence of the two fibres' properties after leaching (chrysotile possibly becoming less active and crocidolite more active in the lung) could help explain some differences between laboratory and animal findings.
• Limitations the authors state:
  • The authors stated that the role of complement activation and chemotactic factor generation in causing asbestosis must remain a matter for speculation.
  • The authors noted that the drop in response at high chrysotile concentrations could reflect a common high-dose effect, adsorption of chemotactic material onto excess fibre, or a toxic effect on the neutrophils. The cause was not established.

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: Chrysotile, Crocidolite.

Related studies

• Time course of chemotactic factor generation and the corresponding macrophage response to asbestos inhalation — D.B. Warheit, L.H. Hill, et al. (1986)
• Neutrophil chemotactic factor release and neutrophil alveolitis in asbestos-exposed individuals — A.A. Hayes, A.H. Rose, et al. (1988)
• Asbestos-induced release of a human alveolar macrophage-derived neutrophil chemotactic factor — A.A. Hayes, T.J. Venaille, et al. (1990)
• Pleural mesothelial cells stimulated by asbestos release chemotactic activity for neutrophils in vitro — V.B. Antony, C.L. Owen, et al. (1989)
• Pulmonary macrophages are attracted to inhaled particles through complement activation — D.B. Warheit, L.H. Overby, et al. (1988)
• Activation of the alternative complement pathway and generation of chemotactic factors by asbestos — M.R. Wilson, H.R. Gaumer, et al. (1977)

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