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 mu g/L. The results were compared to an age- and sex-matched control group with a mean blood lead level of 64.3 mu g/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.