HLA-A and B antigen frequencies in an asbestos exposed population with normal and abnormal chest radiographs

Our plain-English summary of HLA-A and B antigen frequencies in an asbestos exposed population with normal and abnormal chest radiographs, by C. Darke, M.M. Wagner, G.H. McMillan (Tissue Antigens, 1979).

The study

• Authors: C. Darke, M.M. Wagner, G.H. McMillan
• Journal: Tissue Antigens
• Published: 1979;13(3):228-32
• Cited by: 18 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Previous studies of HLA antigen frequencies in asbestos related pulmonary fibrosis have suggested some weak associations both with susceptibility to the disease (B12 and B27) and protection from the disease (B18 and Bw35). HLA typing was performed on a further series of 64 asbestos workers with no chest abnormality and 166 workers with various radiographic changes, 78 having pulmonary fibrosis. The results fail to give statistical confirmation of these associations although B27 was twice as frequently associated with pulmonary fibrosis and diffuse pleural thickening. Analysis of the combined data from this and four other studies failed to show any consistent associations.

In plain English

This study measured HLA antigens, inherited tissue-type markers, in 230 men exposed to asbestos at a Royal Naval Dockyard in Great Britain. Of these, 64 had normal chest X-rays and 166 had X-ray changes, including 78 with pulmonary fibrosis. They were compared with each other and with 298 unexposed blood donors and hospital staff. Earlier studies had suggested links between certain types (B12, B27, B18, Bw35) and asbestos-related fibrosis. A few differences appeared, but none remained significant after allowing for the number of antigens tested. B27 was found in 14.1% of workers with pulmonary fibrosis and 7.6% of workers with normal X-rays or limited pleural thickening, a difference that was not statistically significant. Pooling the results with four earlier studies, the authors found no consistent associations. For B27 they described a marginal increase. The pooled relative risk was 1.56 (P = 0.03) against unexposed controls, and 2.24 (P = 0.008) against exposed workers once a Finnish study was excluded. The authors noted that the studies differed in selection and diagnosis, and that the others studied factory workers.

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: Genetic association study: HLA typing of asbestos-exposed workers grouped by chest X-ray findings, compared with each other and with non-exposed controls, plus a combined relative risk analysis with four earlier studies
• Who was studied: 230 asbestos-exposed dockyard workers selected from a Royal Naval Dockyards survey. 64 had no chest abnormality and 166 had X-ray changes, of whom 78 had pulmonary fibrosis (small opacities). Controls were 298 non-exposed blood donors and hospital staff from Bristol and Exeter, South West England.
• Exposure: Heavy continuous or intermittent asbestos exposure during Royal Naval Dockyard employment. Fiber type is not specified.
• Main results:
  • HLA-B8 was found in 19.6% of the combined group with normal X-rays or limited pleural thickening (NLPT), versus 37.2% of the group with small opacities (pulmonary fibrosis), P = 0.017.
  • HLA-B12 was found in 43.5% of the NLPT group, versus 26.2% of the group with pleural calcification, P = 0.046.
  • HLA-Bw16 was found in 1.3% of all asbestos workers, versus 6.4% of non-exposed controls, P = 0.008.
  • None of these three differences (B8, B12, Bw16) was significant after correction for the number of antigens tested.
  • B27 was found in 7.6% of the NLPT group, compared with 14.1% of the group with small opacities (relative risk 1.99) and 16.9% of the group with diffuse pleural thickening (relative risk 2.47). This was not statistically significant.
  • Combined with four other studies, the data did not confirm a disturbance in B12, B18 or Bw35 frequency. The combined relative risk for B8 was slightly raised (RR = 1.55).
  • Pooled across all five studies, the combined relative risk for B27 was 1.56 (P = 0.03) when non-exposed controls were used.
  • For B27, using exposed workers without fibrosis as controls, the studies showed significant heterogeneity, mainly because of the elevated B27 frequency in the exposed controls of the Finnish study. Excluding the Finnish data, the combined relative risk was 2.24, P = 0.008.
  • The authors described the pooled B27 finding as a marginal increase in pulmonary fibrosis among B27-positive individuals.
  • Among workers with pulmonary fibrosis, B27-positive men had a mean exposure length of 28.0 years and B27-negative men 24.6 years. The difference was not significant.
• The authors' conclusion: The authors concluded that their study showed no statistically significant increase in B27 in asbestos-related pulmonary fibrosis, although B27 was twice as frequent in the groups with small opacities and diffuse pleural thickening. They also concluded that the combined data from this and four other studies failed to show any consistent associations.
• Limitations the authors state:
  • The combined studies differed in how their populations were selected, in diagnostic criteria other than X-ray findings, and in the severity of fibrosis among patients.
  • All other studies were of factory workers, whereas this study's workers were dockyard workers, whose dust levels and dust type may have differed.
  • The significantly shorter exposure in A11-negative workers with no chest abnormality was quite likely a chance finding, given the number of comparisons made.

Topics

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

Medical terms in this study, explained in our Lexicon: Chest X-Ray, Pulmonary Fibrosis, Diffuse Pleural Thickening.

Related studies

• HLA-A and B antigen frequencies and mesothelioma in relation to asbestos exposure — M.M. Wagner, C. Darke, et al. (1983)
• Frequency of HLA antigen in asbestos workers with and without pulmonary fibrosis — C.C. Evans, H.C. Lewinsöhn, et al. (1977)
• High resolution computed tomography and lung function in asbestos-exposed workers with normal chest radiographs — C.A. Staples, G. Gamsu, et al. (1989)
• Findings from high resolution computed tomography of the lung and pleura of symptom free workers exposed to amosite who had normal chest radiographs and pulmonary function tests — S. Neri, A. Antonelli, et al. (1994)
• Cardiorespiratory responses to incremental exercise in patients with asbestos-related pleural thickening and normal or slightly abnormal lung function — A. Miller, A. Bhuptani, et al. (1993)
• Lung function and chest radiograph abnormalities among construction insulators — S.M. Kennedy, S. Vedal, et al. (1991)

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