The hemolytic activity of chrysotile asbestos fibers: a freeze-fracture study

Our plain-English summary of The hemolytic activity of chrysotile asbestos fibers: a freeze-fracture study, by J.P. Pelé, J. Dunnigan, R. Calvert (Environmental Research, 1983).

The study

• Authors: J.P. Pelé, J. Dunnigan, R. Calvert
• Journal: Environmental Research
• Published: 1983;31(1):152-63
• Cited by: 9 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Short asbestos fibers isolated by a sedimentation procedure have a strong hemolytic activity. In the presence of ferritin particles, hemolysis by chrysotile fibers is inhibited at least during the first 10 min. Freeze-fracture studies show that after 20 sec or 2 min of contact between the fibers and the RBC membrane, the intramembranous particles remain randomly distributed over the whole surface of the P-face. On the E-face of the asbestos-treated red blood cell membranes, the number of intramembranous particles is significantly reduced. With the transmission electron microscopy, it is not possible to resolve the trilaminar structure of the ghost membrane around the deeply buried asbestos fibers. It is postulated that the membrane defects brought about by asbestos are caused by the adsorption of one membrane constituent, possibly phospholipids, on the chrysotile fibers.

In plain English

This laboratory study looked at how short chrysotile asbestos fibers break open red blood cells (hemolysis). The fibers were separated from Quebec 4T30 chrysotile and mixed with red blood cells from rats. The mixtures were examined by light microscopy, electron microscopy and freeze-fracture, which exposes protein particles inside cell membranes. Fibers and cells clumped together almost instantly. Within 20 to 30 seconds a few cells were already damaged and hemoglobin was seen outside them. After 5 minutes, emptied cells (ghosts) were numerous. When ferritin was added to the cells before the fibers, the fibers became coated with ferritin particles and hemolysis was inhibited for at least the first 10 minutes. In freeze-fracture images, membrane particles on one face (the P-face) stayed randomly spread and did not cluster. On the other face (the E-face) they fell significantly, by 38% compared with untreated cells. Fibers appeared deeply buried in the cells, as if the membrane wrapped around them. The authors postulated that the membrane defects come from the fibers adsorbing a membrane component, possibly phospholipids. They said the meaning of the E-face reduction was unknown.

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 using light microscopy, transmission electron microscopy, freeze-fracture and freeze-etching of red blood cells exposed to asbestos fibers
• Who was studied: Red blood cells from Long Island rats weighing 250-300 g, washed and used as a 4% suspension. The number of rats is not given. Particle counts used 11 to 16 micrographs per group.
• Exposure: Short chrysotile fibers isolated from Quebec 4T30 chrysotile by sedimentation, with a surface charge (zeta potential) of +52 mV at pH 7.3. They were tested at concentrations of 1000 and 400 per ml (the unit is garbled in the scan) and for contact times from 20 seconds to 10 minutes. Some experiments added ferritin before or after the fibers.
• Main results:
  • When rat red blood cells were mixed with the fibers, aggregates of cells and fibers formed almost immediately.
  • In electron microscopy, 20-30 seconds after fibers were added, a few cell membranes were already damaged and hemoglobin was seen outside the cells.
  • After 5 minutes of contact, emptied cells (ghosts) were numerous.
  • When ferritin was mixed with the cells before the fibers were added, hemolysis was inhibited for at least the first 10 minutes and no aggregates formed.
  • When ferritin was added after the fibers, aggregates and hemolysis occurred. Ferritin added immediately after aggregates formed was seen inside the leaky cells.
  • In freeze-fracture of cells after 20-30 seconds of contact with fibers, membrane particles on the P-face were randomly distributed, even near the fiber imprints, and no clusters were seen. P-face counts were 3649 plus or minus 106 particles per square micrometer in treated cells and 3612 plus or minus 99 in controls, with no statistical difference.
  • On the E-face, asbestos-treated cells had 322 plus or minus 20 particles per square micrometer versus 516 plus or minus 47 in controls. This was a significant 38% decrease (P less than 0.0025).
  • The fibers penetrated deep into the cell, and the membrane tended to wrap itself around them.
  • The usual three-layered (trilaminar) membrane structure could not be resolved around the engulfed fibers.
• The authors' conclusion: The authors postulated that the membrane defects caused by asbestos are due to adsorption of one membrane constituent, possibly phospholipids, on the chrysotile fibers. They said further studies are needed to identify which membrane component is involved.
• Limitations the authors state:
  • The authors stated that the significance of the reduced particle count on the E-face is unknown. They also said they could not answer whether the fibers leach proteins from the membrane.
  • The authors noted that fixation procedures can change particle counts in red cell membranes. They argued this did not explain the difference because controls and treated cells were prepared the same way.
  • The authors stated that further studies are needed to determine which membrane component is involved in hemolysis by asbestos.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Chrysotile.

Medical terms in this study, explained in our Lexicon: Chrysotile, Ferritin, Transmission Electron Microscopy (TEM).

Related studies

• A comparative study on the hemolytic action of short asbestos fibers on human, rat, and sheep erythrocytes — J.P. Pelé, R. Calvert (1983)
• Surface charge and hemolytic activity of asbestos — W.G. Light, E.T. Wei (1977)
• Mount St. Helens' volcanic ash: hemolytic activity — V. Vallyathan, M.S. Mentnech, et al. (1983)
• Wollastonite fibers in vitro generate reactive oxygen species able to lyse erythrocytes and activate the complement alternate pathway — M. Governa, L. Camilucci, et al. (1998)
• Haemolytic activity of asbestos and other mineral dusts — G. Macnab, J.S. Harington (1967)
• Hemolysis by chrysotile asbestos fibers. I. Influence of the sialic acid content in human, rat, and sheep red blood cell membranes — J.P. Pelé, R. Calvert (1983)

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