Alterations in Th17 and Treg Lymphocyte Subset in Workers Occupationally Exposed to Lead

Occupational exposure to lead (Pb) may have a deleterious effect on health of the workers. Among the various physiological systems, the immune system is one of the most susceptible targets of lead. Previous studies have been inconclusive in establishing the effect of Pb on the immune system. With this background, the aim of our study was to determine the effect of occupational Pb exposure on workers' immune parameters. A total of 110 individuals who were occupationally exposed to Pb and 97 apparently healthy non-exposed individuals were recruited in this study. Blood lead levels (BLL) were determined by atomic absorption spectrophotometry (AAS). Lymphocyte subsets (Th1, Th17, and Tregs) were analyzed using flow cytometry, and the cytokine levels (IL-2, IL-4, IL-6, IL-10, IL-17, and TNF-α) were determined by ELISA. BLL were found to be significantly higher in the exposed group than non-exposed. A significant increase of CD8 cells (%) was observed in the lead-exposed group, while CD4 cells (%), although higher in the exposed group did not differ significantly. Among the T lymphocyte subsets, proportion of Th1 and Tregs was found to be lower in the exposed group with a significant increase in Th17 (%). Additionally, the levels of estimated cytokines suggested a predominant pro-inflammatory response in Pb-exposed workers with significant increase in IL-4, IL-6, and TNF-α, and a significant decrease in IL-2 and IL-10. IL-17 levels did not show any significant difference between the two groups. Increased Th17/Tregs ratio in the exposed group is also suggestive of an increased pro-inflammatory immune response in the exposed group. In conclusion, Pb exposure may induce functional alteration in the immune cells, which may predispose to other abnormalities.