Immunologic aberrations in asbestos cement workers: dissociation from asbestosis

Our plain-English summary of Immunologic aberrations in asbestos cement workers: dissociation from asbestosis, by R.D. deShazo, D.J. Hendrick, J.E. Diem, et al (The Journal of Allergy and Clinical Immunology, 1983).

The study

• Authors: R.D. deShazo, D.J. Hendrick, J.E. Diem, J.A. Nordberg, Y. Baser, D. Bevier, R.N. Jones, H.W. Barkman, J.E. Salvaggio, H. Weill
• Journal: The Journal of Allergy and Clinical Immunology
• Published: 1983;72(5 Pt 1):454-61
• Cited by: 22 articles, as counted by NIH iCite
• Read it: PubMed · Publisher
• In J-M's library: Johns-Manville's company medical library held a copy (J-M no. 000604).

Abstract

Immunoregulatory disorders have been implicated in the pathogenesis of asbestosis. We therefore compared the immunologic status of a well-characterized group of 31 current and former asbestos-cement workers with that of a group of 52 healthy controls, after adjustments had been made for the possible confounding effects of age, race, and smoking. The asbestos workers had significantly decreased percentages and numbers of both B and T lymphocytes in peripheral blood and a paradoxical IgG hypergammaglobulinemia. Analysis of T-lymphocyte subpopulations revealed that total T-cell numbers (OKT3+), helper-inducer T-cell numbers (OKT4+), and suppressor-cytotoxic T cell numbers (OKT8+) were decreased by similar proportions. These decreases were negatively correlated with time elapsing since the end of exposure to asbestos. In both workers and controls, lymphocyte proliferative responses to phytohemagglutinin (PHA) were correlated positively with the number of OKT4+ cells and negatively with age and serum IgG levels. When adjustments had been made for these confounding variables, no differences in PHA responses were noted between workers and controls. No relationship was detected in the workers between any of the immunologic aberrations noted and (1) radiographic category of pneumoconiosis, (2) estimates of cumulative asbestos exposure, or (3) abnormalities of pulmonary function. These data suggest that the immunologic perturbations we have noted in asbestos-exposed individuals are epiphenomena, unrelated to the pathogenesis of asbestosis itself.

In plain English

The authors compared blood immune measurements in 31 men who currently or formerly worked in the asbestos-cement industry with those of 52 people who had no history of asbestos exposure. The workers' main exposure was to chrysotile asbestos. After adjusting for age where needed, the workers had significantly higher serum IgG levels and significantly fewer circulating B cells and T cells. This included the OKT3+, OKT4+ and OKT8+ T-cell groups, whose absolute numbers were lower by 37%, 39% and 32%. After adjusting for age, OKT4+ cell numbers and IgG, lymphocyte responses to the stimulant PHA did not differ significantly between workers and controls. The T-cell changes were most marked in current workers and least marked in those whose exposure had ended many years before. They were not correlated with cumulative exposure. None of the altered immune measures was correlated with chest X-ray evidence of asbestosis or with lung function. The authors concluded that these immune changes are epiphenomena, unrelated to how asbestosis develops. They noted that their data allow no conclusions about cancer.

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: Cross-sectional comparison of asbestos-cement workers with unexposed controls, adjusting for age, race and smoking
• Who was studied: 31 men currently or formerly employed in the asbestos-cement industry, most (26 of 31) no longer employed. They were compared with 52 control subjects (19 female, 33 male), clerical workers and municipal employees with no history of asbestos exposure. Location and study dates are not stated in the text.
• Exposure: Mainly chrysotile asbestos, which made up 15% to 28% of the cement products manufactured. Workers had a mean cumulative exposure of 2638 particles per cubic foot-months, estimated from total airborne particulate measurements.
• Main results:
  • Serum IgG levels were significantly higher in workers than in controls (Table I means 2221 vs 1334 mg/100 ml).
  • Circulating B cells were significantly decreased in workers compared with controls (percentages 6.5 vs 8.7; absolute numbers 104 vs 171 cells per cubic millimeter).
  • After controlling for age, absolute numbers of OKT3+, OKT4+ and OKT8+ T cells were significantly lower in workers than in controls, by 37%, 39% and 32% respectively.
  • The OKT4+ to OKT8+ cell ratio did not differ between workers and controls.
  • PHA dose-response curves were measured in 21 workers and 50 controls.
  • After adjusting for age, OKT4+ cell numbers and IgG levels, lymphocyte responses to PHA did not differ significantly between workers and controls.
  • Among workers, the decreases in T cells were most marked in current workers and least marked in those whose exposure had ceased many years ago.
  • The T-cell changes were not correlated with estimated cumulative exposure.
  • B-cell numbers and IgG levels were not related to either cumulative exposure or time since exposure.
  • None of the altered immune measures (IgG, B cells, OKT3+, OKT4+, OKT8+ cells) correlated with radiographic evidence of asbestosis among the workers.
  • These immune measures also did not correlate with lung function measures, including FVC.
  • Of 29 workers with chest radiographs, 11 were normal (0/0), 7 equivocal (0/1) and 11 abnormal (1/0 or above). There were no significant differences in the immune measures between these subgroups.
  • Two workers had abnormal levels of circulating immune complexes.
• The authors' conclusion: The authors concluded that the immune changes they found in asbestos-exposed individuals are epiphenomena, unrelated to the pathogenesis of asbestosis itself.
• Limitations the authors state:
  • The data do not exclude the possibility that other immune measures, such as cytotoxic cell numbers or function, are correlated with disease.
  • The data allow no conclusions about whether the abnormalities are relevant to cancer or to autoimmune phenomena associated with asbestosis.
  • The study was probably too small to detect a mild effect of smoking on serum IgG levels.

Topics

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

Medical terms in this study, explained in our Lexicon: Asbestos-Cement, Confounding, Pneumoconiosis, Asbestos Exposure.

Related studies

• Immunologic investigations in asbestos-exposed workers — R.D. deShazo, C.B. Daul, et al. (1986)
• Asbestos toxicity: an immunologic perspective — G.J. Rosenthal, P. Simeonova, et al. (1999)
• Analysis of depressed cell-mediated immunity in asbestos workers — R.D. deShazo, J. Nordberg, et al. (1983)
• Current concepts about the pathogenesis of silicosis and asbestosis — R.D. deShazo (1982)
• Immunologic aspects of pneumoconiosis — R.K. Scheule, A. Holian (1991)
• Radiographic asbestosis is not a prerequisite for asbestos-associated lung cancer in Ontario asbestos-cement workers — M.M. Finkelstein (1997)

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