The Relationship Between Serum Bilirubin Concentration and Inflammatory Cytokines in a Sulfur Mustard Exposed Population

Background: Despite observed post Sulfur Mustard (SM) exposure hemolysis, serum bilirubin concentration doesn’t significantly increase in SM-exposed casualties. The concentration of serum bilirubin can be related to serum levels of inflammatory cytokines. Objectives: In this study, the relationship between the serum levels of Interleukin (IL)-1α, IL-1β, IL-1Ra, Tumor Necrotizing Factor (TNF)-α and IL-6 with serum bilirubin concentration was investigated. Methods: Overall, 368 individuals, who were exposed to SM in 1986, and 127 non-exposed control participants were studied in the context of hematological factors, serum bilirubin and inflammatory cytokines. Total serum bilirubin and direct bilirubin were analyzed using an enzymatic method, while the inflammatory cytokines were evaluated by the enzyme linked immunosorbent assay (ELISA). Results: The concentration of inflammatory cytokines in the exposed group was significantly different compared to the control group, however the serum concentrations of total and direct bilirubin did not differ between the two groups. Among cytokines, other than the relationship between the IL-6 concentrations and bilirubin level, there were no significant correlations between the levels of other cytokines with direct and total bilirubin. Conclusions: Considering the lack of correlation between bilirubin concentrations and levels of inflammatory cytokines other than IL-6, we should identify other confounding factors for lack of increase in bilirubin in SM casualties, despite the observed hemolysis.