Bronchoalveolar lavage analysis, gallium-67 lung scanning and soluble interleukin-2 receptor levels in asbestos exposure

Our plain-English summary of Bronchoalveolar lavage analysis, gallium-67 lung scanning and soluble interleukin-2 receptor levels in asbestos exposure, by G.L. Delclos, D.G. Flitcraft, K.P. Brousseau, et al (Environmental Research, 1989).

The study

• Authors: G.L. Delclos, D.G. Flitcraft, K.P. Brousseau, N.T. Windsor, D.L. Nelson, R.K. Wilson, E.C. Lawrence
• Journal: Environmental Research
• Published: 1989;48(2):164-78
• Cited by: 10 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. 000069).

Abstract

This study examined different markers of lung immunologic and inflammatory responses to previous asbestos exposure. We performed bronchoalveolar lavage (BAL) and gallium-67 (67Ga) lung scans and measured serum and BAL soluble interleukin-2 receptor (IL-2R) and angiotensin-converting enzyme (SACE) levels in 32 subjects with a history of significant asbestos exposure, 14 without (EXP) and 18 with (ASB) radiographic evidence of asbestosis. BAL analysis revealed increases in neutrophils in both ASB and EXP when compared to controls (P less than 0.01), which persisted after adjustment for smoking category. Although significant abnormalities of macrophage and total lymphocyte profiles were not found in the study population, lymphocyte subpopulation analysis revealed elevation of BAL T4/T8 ratios in the entire study group (ASB + EXP) when compared to controls (P less than 0.05), independent of smoking category. 67Ga lung scan activity was increased in 56% of ASB and in 36% of EXP: no correlations between positive scans and different radiological and functional parameters could be found. There was no significant elevation of mean SACE, serum, or BAL IL-2R levels in any of the study categories. These data suggest that asbestos exposure may be associated with parenchymal inflammation, even in the absence of clinical criteria for asbestosis. Abnormalities of gallium uptake and of BAL analysis reflect the clinically inapparent inflammation. The increased BAL T4/T8 ratios observed suggest that abnormal local pulmonary immunoregulation may play a role in the pathogenesis of asbestos-related lung diseases.

In plain English

This study looked for signs of lung inflammation and immune activity in 32 men in Houston who had formerly worked with asbestos end products, mostly as insulators and pipefitters using materials with mixed asbestos fiber types. Eighteen had chest X-ray evidence of asbestosis and 14 did not. The researchers examined fluid washed from the lungs (bronchoalveolar lavage), performed gallium-67 lung scans, and measured soluble interleukin-2 receptor and serum angiotensin-converting enzyme. Compared with healthy volunteer controls, both groups had more neutrophils, a type of white blood cell, in lung fluid, even after accounting for smoking. In 14 men tested, the ratio of T4 to T8 lymphocytes was higher than in 15 controls. The rise was statistically significant in the asbestosis group but not in the group without asbestosis. Gallium scans were abnormal in 10 of 18 men with asbestosis and 5 of 14 without. The other markers were not significantly raised. The authors concluded that asbestos exposure may be associated with lung inflammation even without asbestosis. They added that whether these tests can identify who is more likely to develop asbestosis awaits further study.

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: Clinical comparison (cross-sectional) of asbestos-exposed men, with and without radiographic asbestosis, against healthy volunteer reference groups, using bronchoalveolar lavage, gallium-67 lung scanning, and blood and lavage-fluid markers
• Who was studied: 32 men with a past history of significant asbestos exposure, recruited from people referred to the authors' institution in Houston, Texas, for evaluation of possible asbestos-associated disease. Eighteen (ASB) had radiographic asbestosis, defined as ILO profusion 1/1 or greater, and 14 (EXP) did not. Mean age was 53.5 years. There were 19 current smokers and 13 lifelong nonsmokers. Controls were a pool of healthy volunteers used as laboratory reference values (N = 182 for lavage cell counts), 15 controls for lymphocyte subsets, and 54 healthy volunteers for serum IL-2R. Study dates were not given.
• Exposure: Former asbestos end-product workers, mostly insulators and pipefitters, whose trades generally used materials containing mixed asbestos fiber types. Mean time since first exposure was 31.9 years and mean duration of exposure was 24.3 years. Fiber levels were not available.
• Main results:
  • In the whole study group (ASB + EXP), lavage neutrophils (PMNs) were increased about fourfold compared with controls: 8 versus 2 × 10^3 cells/ml, P < 0.001.
  • The neutrophil increase was also seen separately in the ASB group (P < 0.01) and the EXP group (P < 0.001), and it persisted after grouping by smoking status.
  • Lavage eosinophil increases were significant only for the whole study group or the EXP group, and disappeared once smoking status was taken into account.
  • No significant abnormalities were found in lavage macrophage or total lymphocyte profiles in the study population.
  • In the 14 study subjects tested (7 EXP, 7 ASB), the lavage T4/T8 ratio was elevated compared with 15 controls: 3.1 versus 1.39, P < 0.01.
  • The T4/T8 elevation was most marked in the ASB subjects (mean ratio 3.9, P < 0.01). In the EXP subjects the increase was not statistically significant (P = 0.09).
  • The increased T4/T8 ratio was mainly due to more T4 cells rather than fewer T8 cells.
  • Gallium-67 lung scans showed abnormally increased uptake in 10 of 18 (56%) men with asbestosis and 5 of 14 (36%) men without asbestosis.
  • An abnormal gallium scan was not correlated with X-ray profusion category, pulmonary function tests, lavage cell profiles, or serum angiotensin-converting enzyme levels.
  • Serum soluble IL-2R geometric mean levels were 675.38 U/ml in the EXP group and 718.11 U/ml in the ASB group, compared with 652.5 U/ml in controls. These differences were not significant.
  • IL-2R in lavage fluid was undetectable in 22 of 24 study samples and in 34 of 36 control samples.
  • Mean serum angiotensin-converting enzyme was within normal limits in each group. Four EXP and four ASB subjects had levels above 35 U/ml, with no significant correlation to other clinical or laboratory parameters.
  • Asbestos bodies were found in sputum and/or lavage fluid in 16 of the 28 subjects tested.
• The authors' conclusion: The authors concluded that asbestos exposure may be associated with lung parenchymal inflammation even when clinical criteria for asbestosis are absent. They also concluded that the raised lavage T4/T8 ratios suggest abnormal local lung immune regulation may play a role in asbestos-related lung diseases.
• Limitations the authors state:
  • Reliable estimates of the workers' asbestos fiber exposure levels were not available.
  • When T4/T8 ratios were broken down by smoking status within the EXP and ASB subgroups, the numbers were too small for statistical comparison.
  • The authors did not measure surface expression of IL-2R on lavage cells. They noted that failing to detect soluble IL-2R in lavage fluid may reflect dilution or assay limitations.
  • How well these tests identify people more likely to develop asbestosis was not established and awaits prospective study.

Topics

Medical terms in this study, explained in our Lexicon: Bronchoalveolar Lavage (BAL), Asbestos Exposure, Macrophage, Inflammation.

Related studies

• Gallium lung scanning and bronchoalveolar lavage in crocidolite-exposed workers — A.A. Hayes, B. Mullan, et al. (1989)
• Gallium scanning in differentiating malignant from benign asbestos-related pleural disease — A.S. Teirstein, P. Chahinian, et al. (1986)
• Gallium scanning in peritoneal mesothelioma — R.R. Armas, S.J. Goldsmith (1985)
• Pulmonary uptake of gallium-67 in asbestos-exposed humans and sheep — R. Bégin, A. Cantin, et al. (1983)
• Unexpected gallium uptake in benign pulmonary pathology. Report of two cases — R.G. McLean, D. Choy, et al. (1984)
• Bronchoalveolar lavage and 99mTc-DTPA clearance as prognostic factors in asbestos workers with and without asbestosis — N. al Jarad, A.R. Gellert, et al. (1993)

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