The brominated flame retardants hexabromcylododecane and tetrabromobisphenol A decrease secretion of interferon gamma from human natural killer cells

Hexabromcyclododecane (HBCD) and tetrabromobisphenol A (TBBPA) are brominated flame retardants that significantly contaminate the environment and are found in human blood samples. Human natural killer (NK) cells are the earliest defense against tumors and viral infections and secrete the cytokine interferon (IFN) gamma. IFN gamma is an important regulator of both the adaptive and innate immune responses. It regulates the function of T lymphocytes, B lypmhocytes, and monocytes. Previously, we have shown that HBCD and TBBPA were able to interfere with the ability of NK cells to lyse tumor target cells. Due to the importance of IFN gamma secretion by NK cells in overall immune system competency, it is important to determine if these compounds also adversely affect the IFN gamma secretion of NK cells. The current study examines the consequences of 24 hour exposures to HBCD and TBBPA on IFN gamma secretion by human NK cells. The results indicate that concentrations of HBCD of 10–2.5 μM caused a complete loss of IFN gamma secretion. Exposures of NK cells to TBBPA at concentrations of 10–2.5 μM also completely blocked secretion of IFN gamma. Supported by NIH grant S06 GM008092‐35