Environmental cigarette smoke exposure modulates IgE levels of Pb-exposed children

Abstract

In urban areas with a predominance of early to mid-20th century housing stock, islands of children possessing blood lead levels (PbB) in excess of CDC guidelines (>10μg/dL) exist. Many of these children are also exposed to environmental tobacco smoke (ETS). The current study examined the impact of Pb-exposure (PbB levels of 1–55μg/dL) with/without concurrent ETS exposure on immune system function in 318 children aged 6–84 months from the urban area of Springfield-Greene County, MO. In this population, 36.5% of children possessed PbB levels >10μg/dL, 62.9% of children came from smoking homes, 51.9% of children were under 2 years of age, and the population was WIC eligible and predominantly of white, non-Hispanic ethnicity. Multiple immune function markers including cell counts, IgE levels, sCD25 (sIL2R) and IL4 concentrations, and titers to common childhood immunizations were analyzed for correlation with Pb and/or ETS exposure. Increased IgE levels (p<0.01) were found in children with PbB levels within CDC Classes II–IV – this finding was primarily attributable to elevated IgE levels in the subpopulation of children with concurrent Pb and ETS exposure. A trend (0.05<p<0.01) of increases in % total T-cells (p=0.06) was also found in children with concurrent elevated PbB levels and ETS exposure. This trend was not found in the subset of children without ETS exposure nor was it present in the analysis of the entire population set. Conversely, alterations in median values for % lymphocytes, % granulocytes, and % activated T-cells across Pb classes were present in the subpopulation of children expose to Pb alone (without concurrent ETS exposure) though a clear trend was not evident. In the entire population set, a statistically significant correlation between ETS and PbB levels was found. This study indicates that prior reports of a correlation between elevated PbB levels and serum IgE levels may be strongly influenced by exposure to ETS. Findings from this study also indicate that Pb is an immune modulator and PbB levels may be influenced by ETS exposure.