Immunological effects of long-term lead exposure among Taiwanese workers

Exposure to lead has been shown to have a deleterious effect on the immune system. However, the findings of previous studies have been inconsistent. This may have been due to the increased susceptibility to intracellular pathogens and increased polyclonal and antigen-specific responses on exposure to lead. The objective of the current study was to evaluate the immune function of long-term workers with lead in a battery manufacturing plant. Junior high school teachers were used as a control group. Our results showed that the percentage of monocytes was significantly higher among lead workers than in the control group, but T8 cell levels were lower. The T4/T8 ratio was significantly higher among lead workers (1.42) than in the control group (1.18). After adjustment for age, gender and disease using multiple linear regression models, the percentage of B-cells and number of lymphocytes, monocytes and granulocytes were all significantly decreased among lead workers compared with the control group. Our findings showed that lead caused a marked immunotoxic and immunosuppressive effect among long-term lead workers.