Dynamics of lymphocyte subsets in children living in an area polluted by polychlorinated biphenyls

Abstract

Immune system development, particularly in the pre-natal and early post-natal periods, has far-reaching health consequences during childhood, as well as throughout life. Exposure to poly-chlorinated biphenyls (PCBs) during pre-natal and early life has been previously associated with changes in the incidence of infectious and allergic diseases in children, and humoral immunity alterations. Lymphocyte immunophenotyping is an important tool in the diagnosis of immunologic and hematologic disorders. This study used a lysed whole blood method for analysis of lymphocyte sub-populations in samples from children born and living in two districts: a highly-contaminated area (Michalovce) and one (Svidnik/Stropkov) with ≈ 2-fold lower environmental PCB levels. The percentages of B-lymphocytes (CD19⁺), activated HLADR⁺CD19⁺ cells, and CD8⁺ T-lymphocytes significantly increased at 6- and 16-months-of-age in both selected regions as compared to in cord blood values (p < 0.001). Levels of CD3⁺ cells increased significantly (from 61 to 65%) in samples from Michalovce (p < 0.01). Levels of CD4⁺ T-lymphocytes declined 10% among 16-month-olds in both regions (Michalovce at p < 0.001 and Svidnik/Stropkov at p < 0.01). Natural killer (NK) cell levels decreased 50% in Michalovce 6- and 16-month-old children and 42% among 6-month-olds in Svidnik/Stropkov (p < 0.001). Compared with the less-contaminated region, Michalovce samples showed significantly higher expression of CD3⁺ T-lymphocytes, B-lymphocytes, and activated B-lymphocytes, whereas NK cells were less expressed. Even after adjustment for selected covariates, e.g., maternal cigarette smoking, age, parity, ethnicity, birth weight, and gender of infant, the levels of CD19⁺, HLADR⁺CD19⁺, and CD3⁻CD(16 + 56)⁺ cells were seen to remain significantly different between the districts. These results showed that early-life environmental PCB exposure was associated with fluctuations in major lymphocyte subsets in children, suggesting that there is a post-natal immune system response to PCB exposures.

Keywords::

• Immunophenotyping
• CD markers
• lymphocytes
• natural killer cells
• polychlorinated biphenyls
• environmental pollution
• cord blood
• infant
• pre-natal exposure
• post-natal exposure

Acknowledgments

This work was supported by the US NIH grant # R01-CA096525, Grant of the Ministry of Health of the Slovak Republic # 2005/31-SZU-09, and the 6^th FP EU research projects “HEIMTSA” (no. GOCE-CT-2006-036913-2) and “INTARESE” (no. GOCE 018385). We wish to thank Mikulas Krnac and Olga Liskova for their technical assistance. We are grateful to our regional cooperators from the Hospitals in Michalovce and in Svidnik for their responsible work within the project and we wish to thank all mothers with children who participated in the project.

Declaration of interest

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.