Changes in free intracellular calcium and production of reactive oxygen metabolites in human leukocytes by soluble and particulate stimuli

Our plain-English summary of Changes in free intracellular calcium and production of reactive oxygen metabolites in human leukocytes by soluble and particulate stimuli, by M. Tuomala, M.R. Hirvonen, K.M. Savolainen (Toxicology, 1993).

The study

• Authors: M. Tuomala, M.R. Hirvonen, K.M. Savolainen
• Journal: Toxicology
• Published: 1993;80(1):71-82
• Cited by: 19 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Changes in free intracellular calcium concentration ([Ca2+]i) and in the production of reactive oxygen metabolites (ROM) were studied in human polymorphonuclear leukocytes (PMNL) exposed to graded concentrations of formyl-methionyl-leucyl-phenylalanine (fMLP), a chemotactic peptide, phorbol myristate acetate (PMA), a stimulator of protein kinase C (PKC), quartz, or chrysotile. fMLP, quartz, and chrysotile induced a concentration-dependent elevation in [Ca2+]i. PMA did not affect [Ca2+]i. fMLP caused a rapid and transient increase in [Ca2+]i, whereas that caused by quartz or chrysotile was slow and sustained. fMLP, PMA and quartz all caused a concentration-dependent ROM production in PMNL. Chrysotile also caused a concentration-dependent increase in ROM production, but the slope of the curve was more gentle, with the maximum response being only 25% of that caused by the other stimuli. fMLP caused a rapid and transient peak in ROM production at 5 min, PMA a peak at 15 min, whereas quartz and chrysotile induced a biphasic ROM production with peaks at 5 and 20 min, and at 18 and 28 min, respectively. These results suggest that [Ca2+]i may have an important role in the production of ROM by PMNL after an exposure to fMLP, quartz, or chrysotile, and that the involvement of PKC in ROM production is possible.

In plain English

This was a laboratory experiment on cells, not a study of people or workers. The authors isolated white blood cells called polymorphonuclear leukocytes from the blood of healthy adult donors. They exposed the cells to fMLP (a chemical attractant), PMA (a chemical that stimulates the enzyme protein kinase C), quartz dust, or a standard UICC sample of chrysotile asbestos. They measured calcium inside the cells and the cells' output of reactive oxygen metabolites, which are damaging forms of oxygen. Chrysotile raised cell calcium slowly and steadily, by at most about 65% above the starting level. It also increased oxygen metabolite output, but its maximum was about 25-30% of the maximum caused by fMLP, PMA or quartz, with peaks at 18 and 28 minutes. Quartz roughly doubled cell calcium at 500 micrograms per ml, the highest concentration used in the calcium measurements. PMA did not change calcium. With fMLP, quartz and chrysotile, the rise in calcium came before the increase in oxygen metabolites. The authors concluded that cell calcium may play an important role in this oxygen metabolite production. They said the reasons for the differing responses remained open.

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 on isolated human white blood cells; each measurement was repeated three times in duplicate
• Who was studied: Human polymorphonuclear leukocytes (a type of white blood cell) isolated from venous blood of healthy adult donors, studied at the National Public Health Institute, Kuopio, Finland; the number of donors is not given
• Exposure: Chrysotile asbestos (UICC standard sample Chrysotile A) at 1-500 micrograms per ml for the calcium measurements and 25-1000 micrograms per ml for the oxygen metabolite measurements. It was compared with quartz dust (Min-u-sil), the peptide fMLP and PMA.
• Main results:
  • In chrysotile-exposed cells, calcium rose with concentration up to 10 micrograms per ml and then levelled off, with a maximum increase of about 65% above the basal level
  • The chrysotile-induced calcium rise in the cells was slow at first and then sustained, similar to quartz
  • In chrysotile-exposed cells, the maximum increase in reactive oxygen metabolite production was about 25-30% of the maximum caused by fMLP, PMA or quartz
  • Chrysotile produced reactive oxygen metabolites in two phases, with peaks at 18 and 28 minutes after stimulation
  • In the calcium measurements on quartz-exposed cells, 25 micrograms per ml raised cell calcium by 10-15%. The maximum increase, approximately twofold, occurred at 500 micrograms per ml, the highest concentration used for this measurement.
  • The highest concentration of fMLP raised cell calcium from 139 to 594 nM. PMA had no effect on cell calcium.
  • With fMLP, quartz and chrysotile, oxygen metabolite production increased after the rise in cell calcium
• The authors' conclusion: The authors concluded that free calcium inside the cells may play an important role in oxygen metabolite production by these white blood cells. They also concluded that involvement of protein kinase C is likely.
• Limitations the authors state:
  • The authors stated that the reason for the differences in calcium and oxygen metabolite responses to the different stimuli remained open
  • The authors noted that cloudiness (turbidity) from added dust made the apparent baseline calcium reading lower for quartz and chrysotile. They stated that the true baseline was the same in all cases.

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, Biphasic Mesothelioma.

Related studies

• Production of reactive oxygen species by man-made vitreous fibres in human polymorphonuclear leukocytes — M. Ruotsalainen, M.R. Hirvonen, et al. (1999)
• Mineral fiber-induced leukocyte activation: the role of intra- and extracellular calcium — M. Ruotsalainen, J. Naarala, et al. (1995)
• Cellular mechanisms of reactive oxygen metabolite generation from human polymorphonuclear leukocytes induced by crocidolite asbestos — T. Ishizaki, E. Yano, et al. (1997)
• Crocidolite-induced reactive oxygen metabolites generation from human polymorphonuclear leukocytes — T. Ishizaki, E. Yano, et al. (1994)
• Chemiluminescent detection of induced reactive oxygen metabolite production of human polymorphonuclear leucocytes by anthophyllite asbestos — T. Iwata, N. Kohyama, et al. (2002)
• Production of reactive oxygen metabolites induced by asbestos fibres in human polymorphonuclear leucocytes — M. Hedenborg, M. Klockars (1987)

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