11.16 - Assessment of Innate Immunity

Abstract

The innate immune system maintains homeostasis and health as the first response to invading pathogens, allergens, toxicants, and wound damage. Many xenobiotics have been demonstrated to have immunotoxic effects on the functioning of the innate immune system. Assessing the effects of a xenobiotic on innate immunity is important to understand the mechanism of action of the agent and may be an important part of the overall immunotoxicity evaluation to provide a risk assessment for assurance of human safety or identification of environmental limits. This chapter provides a brief introduction to the innate immune system and an overview of examples of xenobiotic agents with effects on innate immunity. The chapter reviews strategies and methods for assessment of components of the innate immune system, including a tiered approach to in vivo toxicology studies that takes into account whether the xenobiotic of interest is an unknown, suspected, or known immunotoxicant. Methods for the evaluation of immune status and function are described, including measurement of soluble and cellular components, functional assessments using cell-based assays, and host resistance assays. The chapter concludes with a brief overview of in vitro approaches for use in screening or for gaining a more in-depth understanding of immunotoxicant mechanisms of action.