The overall goals of my research program are to understand the mechanisms by which chemicals of environmental significance interact with the immune system. Such interactions may result in altered immune function leading to decreased resistance to infectious diseases and increased susceptibility to cancer. We are especially interested in chemicals that act as ligands for the Ah receptor (AhR). Such chemicals include the polychlorinated dioxins, of which 2,3,7,8-tetrachlorodobenzo-p-dioxin (TCDD) is the most toxic, and polychlorinated biphenyls (PCB), which represent widespread environmental contaminants. We are also interested in studying the immunomodulatory effects of natural, food-derived AhR ligands. The majority of our studies involve the use of animal models, including transgenic and gene knock-out mice, to understand how the immune system in altered after exposure to these chemicals. Our recent finding that TCDD prevents the development of Type-1 diabetes in NOD mice without any overt side-effects demonstrates the adage that “one man’s poison is another man’s cure” and we plan to use this model extensively in the future. Multi-color flow cytometry is used extensively in our studies to determine the effects of chemical exposure on the activation and differentiation of individual immune cells. We also use genomic approaches to determine changes in gene expression that are induced by these chemicals.