Sequential immunological studies on an asbestos-exposed population. I. Factors affecting peripheral blood leucocytes and T lymphocytes

Our plain-English summary of Sequential immunological studies on an asbestos-exposed population. I. Factors affecting peripheral blood leucocytes and T lymphocytes, by M.M. Wagner, M.J. Campbell, R.E. Edwards (Clinical and Experimental Immunology, 1979).

The study

• Authors: M.M. Wagner, M.J. Campbell, R.E. Edwards
• Journal: Clinical and Experimental Immunology
• Published: 1979;38(2):323-31
• Cited by: 25 articles, as counted by NIH iCite
• Read it: PubMed · Free full text

Abstract

Peripheral blood leucocyte counts, and E binding rosettes were measured on 138 men on five separate occasions. Little effect was seen from age, or length of asbestos exposure. Overall the most marked effect was that obtained from smoking. Most relevant was an increase in percentage of E-rosettes read after 1 1/2 hrs, which was obtained in the group of those with radiological evidence of fibrosis who smoked. Restricted to subjects with small opacities, those who smoke have a significantly higher (P less than 0.05) percentage E 1 1/2 hr rosettes than those who do not smoke. (Percentage E rosettes read overnight remained unaltered by smoking or X-ray). This increase was found on each occasion that it was measured. Since the absolute number of T lymphocytes rosetting at 1 1/2 hr did not increase, it is suggested that there is either no stimulation of the central pool of T lymphocytes or a decrease in the absolute number of T lymphocytes which could only rosette overnight.

In plain English

This four-year longitudinal study of 138 men from a Naval dockyard reported white blood cell counts and T lymphocytes measured on five occasions, the last five of seven twice-yearly surveys. T lymphocytes were counted as 'E rosettes' read after 1½ hours and overnight. Men were grouped by chest X-ray (normal, pleural change, or small opacities), and smoking was recorded. Age and length of asbestos exposure had little effect. Smokers had total white cell counts on average 1200 higher than non-smokers. Among men with small opacities, smokers had a significantly higher percentage of T lymphocytes rosetting at 1½ hours than non-smokers (p less than 0.05). This small difference was seen at each survey, but the absolute number of these cells was comparable to that in smokers with normal X-rays. Compared with the overall figures from the November 1977 survey, eleven mesothelioma patients had significantly lower percentages of lymphocytes and of 1½-hour rosettes (both p less than 0.01). The authors called the smokers' difference 'hardly significant' and noted greater-than-expected rosette variation and insufficient comparison with comparable unexposed men.

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: Longitudinal (repeated-measures) study of an asbestos-exposed working population over a four-year period. This report covers the last five of seven twice-yearly blood surveys.
• Who was studied: 138 men, the majority still working in a Naval dockyard. They were chosen from earlier dockyard survey participants. A small group of unexposed controls was included and pooled with the exposed men who had normal X-rays. Sporadic cases of mesothelioma (11 patients) were also included. Blood was taken in May and November each year (the figure shows 1975 to 1978).
• Exposure: Asbestos exposure in Naval dockyard work. No fiber type was named. The study considered length of exposure, smoking, age, chronic bronchitis and hay fever. Men were classified by chest X-ray findings: limited or diffuse pleural thickening, pleural calcification, and small opacities.
• Main results:
  • Age and length of asbestos exposure had little effect on the measurements.
  • Across the whole data, white blood cell count showed a non-significant decline with age of 48 cells per year.
  • Across the whole data, total white blood cell count was on average 1200 higher in smokers than in non-smokers (p less than 0.05).
  • At the one survey where this was asked, men who had smoked a cigarette that morning had a total white cell count 600 cells higher than those who had not.
  • Chronic bronchitis and hay fever did not affect any of the measurements.
  • The percentage of T lymphocytes rosetting at 1½ hours was elevated in smokers with small opacities (69.1% in Table 4, 21 men) compared with the other groups (p less than 0.07).
  • Among men with small opacities only, smokers had a significantly higher percentage of 1½-hour rosettes than non-smokers (p less than 0.05). The non-smokers' figure was 65.5% in Table 4, from 10 men.
  • In smokers with small opacities, the absolute number of these 1½-hour T lymphocytes was comparable to that of smokers with normal X-rays (Table 4: 1658 and 1659).
  • The differences were small and only one showed evidence of statistical significance, but they were similar at each survey.
  • The percentage of T lymphocytes read overnight did not change in any of these groups.
  • In the pleural change group, no difference similar to that in the small opacity group was seen. However, ex-smokers with pleural change (10 men) resembled the smokers with small opacities, with a consistent non-significant rise in 1½-hour rosettes.
  • The 11 mesothelioma patients were compared with the overall figures from the November 1977 survey. Their percentage of lymphocytes (23.3%) and percentage of 1½-hour E rosettes (58.9%) were significantly decreased (both p less than 0.01). The rise in their white cell count was not significant.
  • In the mesothelioma patients, E rosette percentages were not related to prognosis. Two patients had normal 1½-hour rosettes 2 and 3 months before death.
  • 'Sticky' monocytes were seen on at least one occasion in 26 of 39 men with small opacities and in 16 of 36 men with normal X-rays. The difference was significant when compared with all men without small opacities (45 of 99).
• The authors' conclusion: The absolute number of 1½-hour rosetting T lymphocytes did not increase. From this, the authors suggested either that the central pool of T lymphocytes was not stimulated, or that the number of T lymphocytes able to rosette only overnight had decreased. They described the consistent difference in smokers with small opacities as hardly significant. They thought that counting more rosettes and assessing monocyte contamination better might make it possible to identify workers with an active immunological process.
• Limitations the authors state:
  • Variation in the E rosette technique was greater than expected, despite efforts to standardize the methods.
  • Unidentified factors other than smoking may have affected the population.
  • Some groups were small and overlapping. Because unexposed men of the right age were hard to find, the small control group was pooled with exposed men with normal X-rays.
  • Comparison with an unexposed control group of men of comparable age, with blood taken under similar circumstances, was not sufficient.
  • Most men with small opacities showed only slight evidence of fibrosis on X-ray.
  • Diagnosis was based on X-ray criteria only.
  • It was impractical to allow for physical activity.
  • Cell viability was not checked during the surveys because of shortage of time.

Topics

Medical terms in this study, explained in our Lexicon: Asbestos Exposure, Fibrosis.

Related studies

• Sequential immunological studies in an asbestos-exposed population. II. Factors affecting lymphocyte function — M.J. Campbell, M.M. Wagner, et al. (1980)
• Activation-induced cell death in human peripheral blood lymphocytes after stimulation with silicate in vitro — T. Aikoh, A. Tomokuni, et al. (1998)
• The ability of inflammatory bronchoalveolar leucocyte populations elicited with microbes or mineral dust to injure alveolar epithelial cells and degrade extracellular matrix in vitro — K. Donaldson, J. Slight, et al. (1988)
• Exposure to asbestos: correlation between blood levels of mesothelin and frequency of micronuclei in peripheral blood lymphocytes — V. Marini, L. Michelazzi, et al. (2011)
• Reduction of chrysotile asbestos-induced genotoxicity in human peripheral blood lymphocytes by garlic extract — K. Bhattacharya, S. Yadava, et al. (2004)
• Kinetics of the bronchoalveolar leucocyte response in rats during exposure to equal airborne mass concentrations of quartz, chrysotile asbestos, or titanium dioxide — K. Donaldson, R.E. Bolton, et al. (1988)

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