Decrease of CD4+ T-lymphocytes in children exposed to environmental lead

The effects of environmental lead on the immune system of young children were assessed by determining the peripheral blood lymphocytes CD3⁺, CD4⁺, CD8⁺, B(CD19⁺) counts, and natural killer (CD16⁺ CD56⁺) cells in 35 preschool children whose mean blood lead level was 140.6 μg/L. The results were compared to an age- and sex-matched control group with a mean blood lead level of 64.3 μg/L. Compared to the controls, a significant reduction in the percentage of CD4⁺ cells and a significant increase of CD8⁺ cells were seen in the high-lead group. The negative correlation between the percentage of CD4⁺ cells and blood lead levels was found to be significant (p<0.01). These results suggest that exposure to environmental lead might result in alterations in the immune function of young children.