Increased memory T cell populations in Pb-exposed children from an e-waste-recycling area

Chronic exposure to heavy metals could affect cell-mediated immunity. The aim of this study was to explore the status of memory T cell development in preschool children from an e-waste recycling area. Blood lead (Pb) levels, peripheral T cell subpopulations, and serum levels of cytokines (IL-2/IL-7/IL-15), relevant to generation and homeostasis of memory T cells were evaluated in preschool children from Guiyu (e-waste-exposed group) and Haojiang (reference group). The correlations between blood Pb levels and percentages of memory T cell subpopulations were also evaluated. Guiyu children had higher blood Pb levels and increased percentages of CD4⁺ central memory T cells and CD8⁺ central memory T cells than in the Haojiang group. Moreover, blood Pb levels were positively associated with the percentages of CD4⁺ central memory T cells. In contrast, Pb exposure contributed marginally in the change of percentages of CD8⁺ central memory T cells in children. There was no significant difference in the serum cytokine levels between the e-waste-exposed and reference children. Taken together, preschool children from an e-waste recycling area suffer from relatively higher levels of Pb exposure, which might facilitate the development of CD4⁺ central memory T cells in these children.