T-suppressor Cells Significantly Elevated among Asbestos Workers

Asbestos workers have been plagued with mesothelioma and other diseases for some time now

, and continued vigilance is required if we are ever to solve this problem. One interesting study is called, "'B-Readers' and Asbestos Medical Surveillance" by Ducatman, Alan M. MS, MD; Yang, CDR William N. MD, MPH; Forman, Samuel A. MD, MPH - Journal of Occupational Medicine: August 1988 - Volume 30 - Issue 8. Here is an excerpt: "Abstract - B-readers" certified in International Labor Office methodology interpret large numbers of randomly distributed asbestos medical surveillance roentgenograms of US Navy employees. Analysis of 23 participating observers, interpreting more than 105,000 radiographs, demonstrated a 300-fold prevalence range of perceived "definite" pulmonary parenchymal abnormalities. There was an evident geographic component to interpretation habits, with East and West Coast observers more likely to interpret films as abnormal than observers from the midcontinent. The most expert observers, a group who instruct the course leading to National Institute for Occupational Safety and Health certification in International Labor Office methodology, also perceived fewer abnormalities than other readers or coastal observers. Instructors still exhibited a sevenfold prevalence range of positive interpretation. Under usual surveillance conditions, the habits of B-readers appear to have a major impact upon the diagnosis of asbestosis from roentgenograms. Certification in B-reading should not be the only quality assurance for radiographic surveillance programs, medical decision-making, epidemiologic comparisons, nor related legal activities."

Another interesting study is called, "High frequency of immune dysfunctions in asbestos workers and in patients with malignant Mesothelioma" by Frances Lew, Peter Tsang, James F. Holland, Noel Warner, Irving J. Selikoff and J. George Bekesi - Journal of Clinical Immunology - Volume 6, Number 3, 225-233. Here is an excerpt: "Abstract - We have examined the primary immune responses, the numbers of total T (T11+) cells, T-helper (T4+) cells, T-suppressor (T8+) cells, and natural killer (NK) (Leu7+) cells, in 118 healthy control subjects and compared the data to those obtained from 20 patients with clinically diagnosed malignant mesothelioma and 375 long-term asbestos workers without neoplasia. The absolute numbers of total T (T11+) and T-helper (T4+) cells were normal in asbestos workers without neoplasia but were significantly reduced in patients with mesothelioma. T-suppressor (T8+) cells, on the other hand, remained unchanged in the patients but were significantly elevated among the asbestos workers. This resulted in a marked reduction in T-helper (Th) to T-suppressor (Ts) ratios in mesothelioma patients and in asbestos workers. Seventy percent of the mesothelioma patients (14 of 20) had significantly depressed NK-cell activity which could be augmented but not normalized by coincubation in patients'' peripheral blood lymphocytes (PBL) with interferon (IFN). Among the asbestos workers three distinctive subgroups could be identified: heightened (H-NK), normal (N-NK), and low (L-NK) NK activity. The NK activity of the L-NK group could be stimulated but not normalized by coincubation with IFN, a finding closely resembling that in malignant mesothelioma patients. Phenotyping of the circulating NK cells revealed a unique Leu7+ subset in increased numbers with a brightly fluorescent property in stable mesothelioma patients with relatively stable or slowly progressive disease and in more than 30% of the asbestos workers. The reduced Th/Ts ratio and NK-cell function among these asbestos workers at high risk may be a direct consequence of asbestos exposure and might not be related to neoplastic processes."

A third study is called, "The Method Used by the U.S. Public Health Service for Enumeration of Asbestos Dust on Membrane Filters" by G. H. Edwards and J. R. Lynch -

U.S. Department of Health, Education, and Welfare, Public Health Service, Bureau of Disease Prevention and Environmental Control, National Center for Urban and Industrial Health, Occupational Health Program, 1014 Broadway, Cincinnati, Ohio - Ann. occup. Hyg., Vol. 11, No. 1, pp. 1-6, 1968. Here is an excerpt: "Samples of air-borne mineral dusts are collected by drawing air through cellulose ester membrane filters. Particles smaller than nominal pore size are retained. Varying sampling rate and filter holder controls the distribution of dust across the filter face. Samples are mounted on standard microscope slides using a high viscosity solution of membrane filter material in a mixture of diethyl oxalate and dimethyl phthalate to render the filter transparent. The mount is stable for 2830 days, but after this period migration of the dust particles causes a loss of areal concentration.

The grain and fiber dust particles, which lie on the surface of the filter, are counted with a phase contrast microscope, using 10X eye-pieces and a 4 mm "high-dry" objective. The field area is delineated with a Porton graticule. Count data are recorded in a form allowing data reduction and statistical analysis by electronic computer. The method, although not suitable to determine compliance with the threshold limit value for asbestos that was developed from a different enumeration method, is highly suited for developing basic data for a more precise recommendation of the limit for asbestos."

We all owe a debt of gratitude to these fine researchers for their important work. If you found any of these excerpts helpful, please read the studies in their entirety.

T-suppressor Cells Significantly Elevated among Asbestos Workers

By: Montwrobleski77

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