Binding of immunoglobulin and activation of complement by asbestos fibers

Our plain-English summary of Binding of immunoglobulin and activation of complement by asbestos fibers, by P. Hasselbacher (The Journal of Allergy and Clinical Immunology, 1979).

The study

• Author: P. Hasselbacher
• Journal: The Journal of Allergy and Clinical Immunology
• Published: 1979;64(4):294-8
• Cited by: 33 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Asbestos fibers adsorbed IgG from whole human serum in amounts comparable to that taken up by crystals of calcium pyrophosphate or hydroxyapatite, but less than that adsorbed by crystals of monosodium urate monohydrate. Chrysotile asbestos was much more active in binding IgG than was amphibole asbestos. The electrophoretic mobility of adsorbed IgG was a function of the surface charge of the crystal studied. Negatively charged fibers adsorbed cationic IgG, and positively charged fibers adsorbed anionic IgG. Complement activation by asbestos, as judged by electrophoretic conversion of C3, was similar for all fiber types tested. Properdin factor B was also activated in the presence of asbestos. Activation of both properdin factor B and C3 was only partially inhibited by ethylene glycol tetraacetic acid, demonstrating that activation was occurring through both the classical and alternative pathways.

In plain English

This was a test-tube study, not a study of people or disease. The author mixed five standard asbestos samples with fresh human serum. Two were chrysotile and three were the amphiboles anthophyllite, crocidolite and amosite. They were compared with urate, calcium pyrophosphate and hydroxyapatite crystals and with zymosan. All five asbestos samples took up the antibody IgG. Chrysotile took up amounts close to calcium pyrophosphate or hydroxyapatite, and the amphiboles took considerably less. Chrysotile held only negatively charged IgG, and the amphiboles only positively charged IgG. Asbestos also activated complement, part of the immune system. In a test of the protein C3, the five samples averaged 37.0%, against 25% in the saline control tube, with no apparent difference by fiber type. These are percentages of an area measured on an electrophoresis plate, which the author cautioned do not exactly equal the share of C3 converted. The chemical EGTA cut the asbestos average to 19.2%. The author concluded that activation occurred through both the classical and alternative complement pathways. The author called the biological consequences of IgG binding not clearly defined.

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 IgG binding and complement activation by asbestos fibers and other crystals in human serum
• Who was studied: Five International Union Against Cancer (UICC) standard asbestos samples (anthophyllite, Canadian chrysotile B, crocidolite, Rhodesian chrysotile A, amosite), tested in fresh human serum. They were compared with monosodium urate monohydrate (MSUM), calcium pyrophosphate dihydrate (CPPD), calcium hydroxyapatite and zymosan.
• Exposure: Asbestos fibers (chrysotile and amphibole types) incubated in fresh human serum. Complement tests used washed crystals at 2.3 mg/ml for 60 minutes at 37 degrees C. IgG tests used 75 mg of unwashed fibers in 0.5 ml serum.
• Main results:
  • All five asbestos preparations bound IgG. The two chrysotile preparations bound amounts close to those bound by CPPD or hydroxyapatite crystals.
  • The amphibole preparations bound considerably less IgG.
  • IgG bound by chrysotile was only the negatively charged (anionic) kind. IgG bound by amphibole asbestos and the non-asbestos crystals was only the positively charged (cationic) kind.
  • C3 conversion was measured as the percent of total area under two precipitin arcs on crossed immunoelectrophoresis, not as the percent of C3 protein converted. On this measure, the saline control tube showed 25%. The mean for the five asbestos preparations was 37.0%, smaller than for MSUM (67%) or zymosan (75%).
  • With EGTA present, C3 conversion by asbestos fell by about half, to a mean of 19.2%. EDTA eliminated C3 conversion in all tubes.
  • No relationship was seen between asbestos fiber type and C3 activation or the effect of EGTA.
  • Factor B activation, measured as percent of area under the gamma-fragment arc, averaged 13.4% for asbestos against 8% in the control. EGTA reduced asbestos activation to half (7.6%).
  • Complement activation did not correlate well with the amount of IgG bound by asbestos.
• The authors' conclusion: The author concluded that, because EGTA only partly inhibited activation of factor B and C3, asbestos activated complement through both the classical and alternative pathways.
• Limitations the authors state:
  • The C3 and factor B measurements do not correspond exactly to the percent of protein converted.
  • The author had less experience with the factor B test than with the C3 test because of a limited supply of antiserum.
  • The biological consequences of IgG binding by asbestos are not clearly defined.
  • The author described as speculative the explanation that surface charge accounts for chrysotile binding more IgG.

Topics

Medical terms in this study, explained in our Lexicon: Chrysotile, Amphibole Asbestos.

Related studies

• Interactions of chrysotile asbestos fibres with the complement system — J.M. Saint-Remy, P. Cole (1980)
• Pulmonary macrophages are attracted to inhaled particles through complement activation — D.B. Warheit, L.H. Overby, et al. (1988)
• C3 activation by monosodium urate monohydrate and other crystalline material — P. Hasselbacher (1979)
• Enhancement of the macrophage oxidative burst by immunoglobulin coating of respirable fibers: fiber-specific differences between asbestos and man-made fibers — I.M. Hill, P.H. Beswick, et al. (1996)
• An epidemiological survey of immunological abnormalities in asbestos workers. II. Serum immunoglobulin levels — A. Lange (1980)
• High serum immunoglobulin G4-related retrosternal fibrosclerosis — K. Kamiya, A. Yoshizu, et al. (2012)

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