5The Capacity of Toxic Agents to Compromise the Immune System (Biologic Markers of Immunosuppression)

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There is increasing awareness and concern within the scientific and public communities that chemical pollutants can suppress immune processes and thus cause increased development of neoplastic and infections diseases. Adverse effects on humans treated with immunosuppressive drugs, numerous studies employing experimental animals, and, to a lesser extent, isolated cases of altered immune function in humans inadvertently or occupationally exposed to xenobiotic substances support these concerns. There is no definitive evidence, as yet, that persons who live near contaminated sites or chemical-manufacturing plants have been immunologically compromised to the extent that they are at increased risk of disease. Nonetheless, there is reason to believe that chemical-induced damage to the immune system might be associated with pathologic conditions, some of which could become detectable only after a long latency. Likewise, exposure to immunotoxic xenobiotics can present additional risk to individuals with immune systems that are already fragile, for example, because of primary immunodeficiency, infancy, or old age.

Most of the experimental data on the effects of xenobiotics on immune function have been generated from animal models. The value of incorporating immunologic data for toxicologic assessment of drugs, chemicals, and biologics for evaluation of human hazard is increasingly accepted. However, as in other areas of toxicology, it is difficult to extrapolate change in a given area of immune function in experimental animals to the incidence of clinical or pathologic effects in humans.

One should not use such a term as ''chemical AIDS" in reference to chemical-induced immune dysfunction. Acquired immune deficiency syndrome (AIDS) is a well-defined disease of known viral etiology that bears no resemblance to potential chemical-induced immune-system changes. AIDS and the effects of commonly used immunomodulating drugs can be useful, however, as examples of the damage that can result from a compromised immune system in animals and humans. In addition, infection with the HIV-1 virus frequently occurs in persons concomitantly affected by other immunosuppressive agents, such as addictive drugs, malnutrition, herpesvirus-6, and Epstein-Barr virus. These agents could serve as cofactors that predispose an individual to HIV-1 infection, as well as confounding the resulting immune response.



https://www.ncbi.nlm.nih.gov/books/NBK235670/