Environmental Immunology: Lessons Learned from Exposure to a Select Panel of Immunotoxicants

Abstract

Exposure to environmental contaminants can produce profound effects on the immune system. Many classes of xenobiotics can significantly suppress or enhance immune responsiveness depending on the levels (i.e., dose) and context (i.e., timing, route) of exposure. Although defining the effects that toxicants can have on the immune system is a valuable component to improving public health, environmental immunology has greatly enhanced our understanding of how the immune system functions and has provided innovative avenues to explore new immunotherapies. This Brief Review focuses on three examples of how immunotoxicology has benefitted the field of immunology, presenting information on the aryl hydrocarbon receptor signaling pathway, the immunomodulatory effects of nanomaterials, and the impact of xenobiotic exposure on the developing immune system. Collectively, contributions from immunotoxicology have significantly enhanced public health and spurred seminal advances in both basic and applied immunology.

Figure 1. Exposure to and effects of environmental toxicants

Toxicants may access the human body through four points of entry (skin, blood, respiratory, and digestive tracts) as shown in blue and affect numerous organs, including the immune system. Toxicants interact with the immune system as a result of deliberate or unintentional exposure, causing either immune activation or immune suppression. Depending on the disease context, this may be either beneficial or detrimental because undesirable immune activation or immune suppression may result in adverse health effects.

Figure 2. AhR expression in immune cells

AhR expression (x-axis) and outcomes of AhR activation (y-axis) by immune cell type.