Immunological aspects of toxicology: premises not promises

Association between serum cotinine concentrations on red blood cell folate concentrations in pregnant women and the mediating role of lymphocytes: an NHANES Study

BACKGROUND

Folate is essential for DNA synthesis and cell division, particularly during pregnancy, where insufficient levels can lead to adverse outcomes like neural tube defects and preterm birth. Tobacco smoke exposure, indicated by serum cotinine levels, is a known risk factor for reduced folate levels. However, the mechanisms underlying this relationship, especially the role of lymphocytes, are not well understood.

OBJECTIVES

This study evaluates the relationship between serum cotinine levels and RBC folate concentrations in pregnant women, explores the mediating role of lymphocyte count, and identifies susceptibility factors that could guide targeted interventions.

METHODS

We conducted a cross-sectional analysis using NHANES data from 1999 to 2018, including 1,021 pregnant women. Serum cotinine levels were used as a biomarker for tobacco exposure, while RBC folate levels indicated long-term folate status. Linear regression, restricted cubic spline, and mediation analyses were performed to assess these relationships.

RESULTS

Serum cotinine levels were significantly negatively correlated with RBC folate concentrations (P < 0.001). A nonlinear relationship revealed more pronounced folate depletion at higher cotinine levels. Mediation analysis showed that elevated lymphocyte count mediated 19.3% of the cotinine-folate association. Factors such as smoking history, advanced maternal age, and heavy alcohol consumption exacerbated this negative effect.

CONCLUSION

Tobacco exposure(as reflected by elevated cotinine levels) significantly reduces folate levels in pregnant women, with lymphocyte count playing a mediating role. These findings underscore the need for targeted public health interventions to mitigate tobacco-related risks during pregnancy.

Phenotypic and functional considerations in the evaluation of immunity in nutritionally compromised hosts

It is well established that proper nutrition is critical to the development of an effective immune system and to enhance the natural immunosurveillance and its effector mechanisms. This enhancement could be mediated either by increasing the frequency and absolute numbers of effector cells or by up-regulation of the cellular mechanisms by which these effector cells carry out their functions. Even in the Western world, large sectors of society often remain undernourished and show suboptimal immune responses, but the relationship between nutrition and immunity is best seen in developing and underdeveloped countries. Although there are many large-scale field studies that investigate the issue of nutrition and immunity, there are relatively few data that go beyond descriptive measurements and directly address how well the immune system functions. This review summarizes interactions between nutrition and immunity and focuses on practical aspects for evaluation of the immune function in the field.

Influence of dietary aluminum on cytokine production by mitogen-stimulated spleen cells from Swiss Webster mice

Swiss Webster mice were exposed to excess dietary aluminum (Al) (1000 micrograms Al/g diet, Al as Al lactate) from conception to 6 months of age. Splenic lymphocytes (10(6) per culture) were incubated for 24 hrs with concanavalin A (5 micrograms/ml). Concentrations of interleukin-2, interferon-gamma and tumor necrosis factor-alpha, as measured in supernatants via ELISA with monoclonal antibodies, were depressed in spleen cells from aluminum treated mice relative to controls. Experiments using the fluorescence activated cell sorter demonstrated a shift in T-cell populations from treated mice with a deficiency of CD4+ cells. These findings suggest a deficit in immune effector cell function after long term in vivo aluminum exposure.