Rheumatoid Factor in Serum of Individuals Exposed to Asbestos

Our plain-English summary of Rheumatoid Factor in Serum of Individuals Exposed to Asbestos, by I.J. Selikoff, B. Pernis, E.C. Vigliani (1965).

The study

• Authors: I.J. Selikoff, B. Pernis, E.C. Vigliani
• Published: Annals of the New York Academy of Sciences (1965)
• Type of article: Journal article
• Our copy: from Johns-Manville's own medical library. The article is still under copyright, so we describe it here rather than post it.

In plain English

This study looked for rheumatoid factors, blood proteins that react with gamma globulins, in the blood serum of asbestos insulation workers. The authors tested sera from 315 male asbestos insulation workers and 103 apparently healthy male controls over 40. The workers had been exposed for 1 to 54 years, and most had asbestosis on X-ray, graded 1 to 3. Workers with tuberculosis, lung cancer or rheumatoid arthritis were excluded. Only workers with X-ray grade 2 or 3 asbestosis differed significantly from the controls. In these grades, 21.0 per cent and 15.9 per cent respectively had a titer of 1:320 or more. More sera reacted with human than with rabbit gamma globulin. Higher rates in workers with over 15 years of exposure were judged to reflect the fact that grade 2 or 3 asbestosis occurs mainly after long exposure. Of eight high-titer sera examined in an ultracentrifuge, only one showed very small amounts of intermediate complexes. Eight rabbits given chrysotile showed no rheumatoid-factor-like activity. The authors concluded that the abnormality is more likely a consequence than a cause of 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 serological comparison of asbestos workers and controls, with a small ultracentrifuge sub-study and an animal experiment in rabbits
• Who was studied: 315 male asbestos insulation workers aged 20 to 78 and 103 apparently healthy male controls; workers with pulmonary tuberculosis, lung cancer or rheumatoid arthritis were excluded; eight adult rabbits in the animal experiment
• Exposure: Work as asbestos insulation workers for 1 to 54 years (fiber type for the workers not stated); most had X-ray asbestosis graded 1 to 3. Rabbits received 200 mg of finely ground chrysotile intravenously, then the same amount by intratracheal injection 48 hours later
• Main results:
  • A significantly different distribution of rheumatoid factor titers from that of controls was found only in workers with X-ray grade 2 or 3 asbestosis
  • Among workers with X-ray grade 2 and grade 3 asbestosis, 21.0 per cent and 15.9 per cent respectively had a hemagglutination titer of 1:320 or more (said to correspond to a frankly positive latex test)
  • Many more sera reacted, and at higher titers, with aggregated human gamma globulin than with aggregated rabbit gamma globulin
  • An increased incidence of rheumatoid factors was found in workers with over 15 years of exposure; the authors considered this to reflect only that grade 2 or 3 asbestosis is found mainly among long-exposed workers
  • Among workers with asbestosis of a given X-ray category, age did not seem to influence the serological findings (Table 3, category 2)
  • Of the eight highest-titer sera examined in the analytical ultracentrifuge, only one showed very small amounts of intermediate sedimenting complexes
  • No rheumatoid-factor-like activity was found in the sera of the eight rabbits treated with chrysotile and bled 8 and 16 days later
• The authors' conclusion: The authors concluded that the serological abnormality, when present, is more likely among the consequences than the causes of asbestosis, and that similar abnormalities occur in pulmonary fibrosis of other origins

Topics

Medical terms in this study, explained in our Lexicon: Insulator, Lung Cancer, Chrysotile.

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