APPROACHES TO THE EVALUATION OF CHEMICAL-INDUCED IMMUNOTOXICITY

The immune system plays a crucial role in maintaining health, however, accumulating evidence indicates that this system can be the target fo r immunotoxic effects caused by a variety of chemicals including the e nvironmental pollutants of polychlorinated biphenyls, chlorinated dibe nzo-p-dioxins, pesticides, and heavy metals. Adverse chemical-induced immunomodulation, which is studied within the discipline of immunotoxi cology, may be expressed either as immuunosuppression/immunodepression or immunoenhancement. The former may be manifested either as decrease d resistance to opportunistic viral, bacterial, fungal, and other infe ctious agents or increased susceptibility to cancer. Immunoenhancement on the other hand may either increase the risk of autoimmune reaction s or result in allergic reactions. This paper attempts to integrate se veral aspects of the immune system that are relevant to the assessment of potentially immunotoxic chemicals.