Dendritic Cells

Dendritic cells (DCs) are immune cells that effectively link the innate and adaptive arms of the immune system. They are considered a professional antigen-presenting cell population because of their unique capacity to induce the activation and differentiation of naive T lymphocytes. Included in this function is the ability to initiate immunogenic as well as tolerogenic responses from T cells, a fundamental step in regulating homeostasis. Numerous subpopulations of DCs have been identified to date, including interstitial DCs, dermal DCs, Langerhans cells (LCs), plasmacytoid DCs (pDCs), and inflammatory DCs. Although relatively little is known about the effects of xenobiotics on DCs, some evidence to date has demonstrated the potential of drugs and environmental chemicals to affect the fate and function of DCs. Because of their central role in the initiation of many adaptive immune responses, modulation of DCs can lead to defective or dysregulated T-cell-mediated immunity and subsequently decreased resistance to infectious disease, or conversely increased incidences of allergies or autoimmune disease. This chapter aims to describe the current knowledge of DCs and the effects of xenobiotics on them. It is certain that the field of DC biology will be an exciting and prosperous area of research in the future for both immunologists and immunotoxicologists and it should not only enhance our basic understanding of how the immune system operates but also yield new potential therapies to improve human health.