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