Natural killer cell activity in asbestos workers. Interactive effects of smoking and asbestos exposure

Our plain-English summary of Natural killer cell activity in asbestos workers. Interactive effects of smoking and asbestos exposure, by R.D. deShazo, J. Morgan, B. Bozelka, et al (Chest, 1988).

The study

• Authors: R.D. deShazo, J. Morgan, B. Bozelka, Y. Chapman
• Journal: Chest
• Published: 1988;94(3):482-5
• Cited by: 7 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. 000899).

Abstract

Both the numbers and function of natural killer (NK) cells in 60 were evaluated in asbestos cement workers grouped by smoking history and chest roentgenogram findings (ILO profusion scores less than 1/0 or greater than or equal to 1/0, or isolated pleural plaques). Worker and control subjects who smoked had smoking histories of less than 27 pack-years, a level of smoking lower than that previously determined to adversely affect NK function. Asbestos workers who did not smoke had percentages and total numbers of NK cells and NK function not different from that of nonsmoker control subjects. Workers who smoked and had evidence of asbestosis (ILO profusion category greater than or equal to 1/0) had significantly lower total numbers of NK cells and mononuclear cell NK activity than did smoker control subjects or smokers with pleural plaques only (p less than or equal to 0.05). Numbers of NK cells and NK cell function were not decreased in either of the asbestos-exposed smoking groups without asbestosis when compared to nonsmoker controls. We conclude that smoking and asbestos exposure interact to decrease mononuclear cell NK function in workers with levels of asbestos exposure sufficient to induce asbestosis. This finding may explain in part the previously reported synergistic effect of smoking and asbestos exposure on the risk of lung cancer. Furthermore, the data presented here clarify previous conflicting reports on NK function where asbestos exposed groups have not been stratified for analysis of data.

In plain English

This study measured natural killer (NK) cells, a type of white blood cell that can kill tumor cells, in blood from 60 asbestos cement workers and 21 control subjects. The controls were clerical and laboratory workers and municipal employees with no history of asbestos exposure. The workers were randomly chosen from 244 workers at two asbestos cement plants in the New Orleans area, where the main exposure was to chrysotile asbestos, and they averaged 33.5 years of exposure. Workers were grouped by smoking status and by chest x-ray findings. The proportion of NK cells did not differ significantly between groups. In nonsmoking workers, NK activity was within the range of control values. Workers who smoked and had x-ray evidence of asbestosis had significantly fewer NK cells in total and significantly depressed NK activity (14±4.3 percent). Only two smoking workers had pleural plaques, too few for statistical analysis. The authors concluded that smoking and asbestos exposure interact to decrease NK function in workers whose exposure was enough to cause asbestosis.

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 blood natural killer (NK) cell numbers and activity in asbestos cement workers and unexposed control subjects, grouped by smoking status and chest x-ray findings
• Who was studied: 60 asbestos cement workers randomly selected from a cohort of 244 workers at two asbestos cement plants in the New Orleans area, and 21 control subjects (clerical and laboratory workers and municipal employees with normal chest x-rays and no history of asbestos exposure). By the table, 46 workers were nonsmokers (16 normal or equivocal x-ray, 14 isolated pleural plaques, 16 asbestosis) and 14 were smokers (6, 2 and 6 in the same groups). Controls were 14 nonsmokers and 7 smokers.
• Exposure: Occupational exposure in asbestos cement manufacture, mainly to chrysotile asbestos, which made up 15 to 28 percent of the cement products. Workers averaged 33.5 years of asbestos exposure.
• Main results:
  • The percentage of NK cells did not differ significantly among worker and control groups, or between smokers and nonsmokers.
  • In all three nonsmoking worker groups, NK activity was within the range of control values: 29.5±5.6 percent in nonsmoking control subjects, and 23±3.8, 22±5.7 and 23±3.9 percent in the worker groups.
  • Among smokers, workers with normal chest x-rays had normal NK activity: 26±3.9 percent, compared with 24±3.1 percent in smoking control subjects.
  • Workers who smoked and had x-ray evidence of asbestosis (ILO category 1/0 or greater) had significantly decreased total numbers of NK (Leu 11 positive) cells.
  • Workers who smoked and had x-ray evidence of asbestosis had significantly depressed NK activity: 14±4.3 percent, p less than or equal to 0.05. The table marks this comparison as against the three other smoker groups.
  • The depressed NK activity in the smoking asbestosis group was consistent among those workers and was seen across all effector-to-target ratios tested.
  • The two workers who smoked and had pleural plaques had NK activity of 51±1.0 percent, which was not depressed compared with smoking control subjects. No statistical test was done for this group.
• The authors' conclusion: The authors concluded that smoking and asbestos exposure interact to decrease NK function in workers with asbestos exposure high enough to cause asbestosis. They suggested this may explain in part the previously reported combined (synergistic) effect of smoking and asbestos exposure on lung cancer risk.
• Limitations the authors state:
  • Only two workers who smoked and had pleural plaques were available, so the authors did not perform statistical analysis for that group.

Topics

Medical terms in this study, explained in our Lexicon: Asbestos Exposure, Asbestos-Cement, Pleural Plaques, Synergistic Effect, Lung Cancer.

Related studies

• Asbestos and cancer: human natural killer cell activity is suppressed by asbestos fibers but can be restored by recombinant interleukin-2 — B.W. Robinson (1989)
• Lymphocyte subsets in subjects exposed to asbestos: changes in circulating natural killer cells — N. al Jarad, M. Macey, et al. (1992)
• Functional Alteration of Natural Killer Cells and Cytotoxic T Lymphocytes upon Asbestos Exposure and in Malignant Mesothelioma Patients — Y. Nishimura, N. Kumagai-Takei, et al. (2015)
• Effects of in vitro asbestos exposure on natural killer and antibody-dependent cellular cytotoxicity — R.G. Barbers, J. Oishi (1987)
• NK cells from malignant pleural effusions are not anergic but produce cytokines and display strong antitumor activity on short-term IL-2 activation — P. Vacca, S. Martini, et al. (2013)
• Asbestos fibres inhibit the in vitro activity of lymphokine-activated killer (LAK) cells from healthy individuals and patients with malignant mesothelioma — L.S. Manning, M.R. Davis, et al. (1991)

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