Association between polychlorinated biphenyls and circulatory immune markers: results from NHANES 1999-2004

Polychlorinated biphenyls (PCBs), a family of persistent toxic and organic environmental pollutants, were associated with multiple organ damages in humans once accumulating. However, association between PCBs exposure and circulatory immune markers were not clear.

Data was collected from participants enrolled in the National Health and Nutrition Examination Survey in 1999-2004. PCBs were categorized by latent class analysis (LCA). Weighted quantile sum (WQS) regression was used to investigate effects of PCBs exposure on circulatory immune markers including leukocyte counts, monocyte-lymphocyte ratio (MLR), neutrophil-lymphocyte ratio (NLR), platelet-lymphocyte ratio (PLR), and systemic immune-inflammation index (SII).

There were 3,109 participants included in the final analysis with blood PCBs levels presented as 3 classes. The high PCBs group had a higher rate of comorbidities. Leukocyte, lymphocyte and neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR) and system immune-inflammation index (SII) were significantly lower in the high PCBs group than in the low PCBs group (all p-values < 0.05). After adjusting for covariant variables, the low PCBs group was positively associated with SII (p = 0.021) and NLR (p = 0.006) in multivariate regression. Significantly negative correlations between PCBs classification and SII (β = -14.513, p = 0.047), and NLR (β = -0.035, p = 0.017) were found in WQS models. LBX028LA showed the most significant contribution in the associations between PCBs and SII, and LBX128LA contributed most significantly to associations with NLR.

Our study adds novel evidence that exposures to PCBs may be adversely associated with the circulatory immune markers, indicating the potential toxic effect of PCBs on the human immune system.