Introduction to Immunotoxicity

Abstract

Recognition that the immune system is vulnerable to adverse effects after exposure to xenobiotics led to the discipline of immunotoxicology and the subsequent addition of immunotoxicology testing to regulatory guidelines for toxicity. Immunotoxic effects can result in immunosuppression, immunostimulation, hypersensitivity, and autoimmunity. The complex nature of the immune system is such that all of these outcomes can potentially affect any number of components of the immune system. In turn, these immunotoxic effects can lead to immune dysfunction that may ultimately contribute to chronic diseases. This chapter will provide a very basic overview of the components of the immune system including innate immunity and adaptive immunity. A number of model systems and assays are described that are commonly used to assess the immunotoxicity of xenobiotics on the immune system. Although these are primarily in vivo based immunoassays, in vitro assays are having a greater role in determining immunotoxic effects and mechanisms of toxicity. Several regulatory agencies have begun to incorporate immunotoxicology testing in their guidelines. The current status of six regulatory guidelines is presented.