Immune Response to Environmental Exposure

Abstract

The immune system is among the most sensitive targets regarding toxicity of environmental pollutants. Having a critical role in maintaining human and animal health, suppression of immunological function can result in increased incidence and severity of infectious diseases. Environmental pollutants can moderate several mechanisms of the immune system at various cellular and subcellular levels, either during immune ontogeny, immune activation, or immune effector functions. Immunotoxic mechanisms induced by representative pollutants compromising innate and adaptive immunity are discussed in this article, such as immunotoxicity of polycyclic aromatic hydrocarbons (PAHs) and polyhalogenated aromatic hydrocarbons (PHAHs) induced through the aryl hydrocarbon receptor, and altered production of reactive oxygen species in phagocytes due to modulation of NADPH oxidase by pesticides, metals, and PAHs. Immune end points used in tier-based toxicity assessment are discussed together with the description of the cellular and subcellular immune processes that provide the rationale of their employment as well as portray their significance and limitations. Some well-documented effects of metals, PAHs, PHAHs, and pesticides on these immune end points in mammals, fish, and invertebrates are discussed along with functional disruption of cell-mediated immunity from pollutant-induced altered cytokine balance during perinatal and early life exposure.