Effects of occupational exposure to mercury vapors on T-cell and NK-cell populations

The counts of lymphocytes, (CD3+) T-cells, (CD4+) T-helper and (CD 8+) T-suppressor and (CD 16+) NK-cells were determined in the peripheral blood of 81 males with a history of occupational exposure to metallic mercury vapors and in 36 males without this exposure. For the determination of T-cell populations monoclonal antibodies were used in indirect immunofluorescence tests. The weighted mean of mercury concentrations in air was 0.028 mg x m-3. Mercury concentration in the urine of the exposed subjects ranged from 10-240 micrograms x l-1, and in blood it was from 4-30 micrograms x l-1. Stimulation of the T-cell line was noted as evidenced by increased number of T-cells by 35% in the workers with exposure to mercury vapors below or by 38% in the workers over 10-years, by increased number of T-helper cells by 42% (p < 0.001) in the workers with exposure below or by 60% (p < 0.001) in the workers over 10 years and by increased number of T-suppressor cells by 85% (p < 0.001) in the workers below or by 96% (p < 0.001) in the workers over 10 years exposure. Lower increase of T-helper cells population than T-suppressor cells population was the cause of decreased value of the T-helper/T-suppressor ratio by about 21% (p < 0.01) in the workers with exposure below and over 10 years. No changes were observed in the T-cell populations between workers with up to 10 and those with over 10 years exposure. The quantitative changes of T-helper cells and T-helper/T-suppressor ratio may represent an immunological indicator of exposure to mercury vapors. Presented changes in human T-lymphocytes population associated with occupational exposure to mercury vapors have been proposed to explain the origin of more frequent autoimmunity induced by mercury.