Immunological effects of occupational exposure to metallic mercury in the population of T-cells and NK-cells.

This paper presents a study of the counts of lymphocytes, (CD3+)T-cells, (CD4+)T-helper and (CD8+)T-suppressor and (CD16+)NK-cells in the peripheral blood of 101 males with a history of occupational exposure to metallic mercury vapours (Hg0) and in 36 males without this exposure. These workers were divided depending on the duration of exposure: 37 males with a short-term history of exposure to Hg0 (up to 10 years) and 64 males with a history of long-term exposure (10 to 37 years). For the determination of T-cell populations monoclonal antibodies were used in indirect immunofluorescence tests. The time weighted average of mercury concentrations in air was 0.028 mg m-3. Mercury concentration in the urine of the exposed subjects ranged from 20-260 micrograms dm-3, and in blood it was from 4 to 72 micrograms dm-3. Stimulation of the T-cell line was noted as evidenced by increased numbers of (CD3+)T-cells, (CD4+)T-helper and (CD8+)T-suppressor cells in the workers with < 10 or > 10 years' exposure to Hg0. Lower increase count of (CD3+)T-cells and (CD4+)T-helper cells than (CD8+)T-suppressor cells was the cause of decreased values in the (CD3+)T/(CD8+)T-suppressor ratio and (CD4+)T-helper/(CD8+)T-suppressor ratio in the workers with < 10 or > 10 years' of exposure. Moreover, no changes were observed in the T-cell populations between workers with < 10 and those with > 10 years' exposure. In addition, statistical analysis of the effects of age and duration of exposure to Hg0 on the studied immunological parameters indicates that exposure duration may affect some of the values. These quantitative changes of T-cell population as well as changes of the (CD3+)T/(CD8+)T-suppressor and (CD4+)T-helper/(CD8+)T-suppressor ratio have been proposed as immunological indicators of exposure to Hg0, which can be used for monitoring and to explain the origin of autoimmunity disorders induced by metallic mercury.