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Published on: November 1, 2013
Immunological effects of chlorinated dibenzo-p-dioxins
1Department of Agricultural Chemistry, Oregon State University, Corvallis, 97331, USA. kerkvlin@ccmail.orst.edu
Abstract:
2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) and structurally similar halogenated aromatic hydrocarbons cause a broad range of immunologic effects in experimental animals including decreased host resistance to infectious disease and suppressed humoral and cell-mediated immune responses. In the mouse, TCDD immunotoxicity has been shown to be an aryl hydrocarbon (Ah) receptor-dependent process. However, despite considerable research, the biochemical and molecular alterations that occur subsequent to Ah receptor activation that lead to altered immune reactivity remain to be elucidated. In addition to immune suppression, TCDD promotes inflammatory responses. This effect may result from an upregulation of the production of inflammatory cytokines such as interleukin-1 and tumor necrosis factor. Nonhuman primates exposed to TCDD show suppressed antibody responses and changes in lymphocyte subsets in the peripheral blood. The immunotoxic effects of TCDD in humans are poorly characterized, and few studies have examined the immune status of individuals with known, documented exposure to TCDD. It is important for laboratory research to focus on defining TCDD-sensitive immunologic biomarkers in animal models that can also be used in human subjects. Understanding the mechanisms that underlie species differences in TCDD immunotoxicity is also of critical importance for extrapolation of effects seen in laboratory animals to man.
Insights
2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) exposure impacts the immune system, causing suppression and inflammation in animals. Further research is needed to understand TCDD
Area of Science:
- Environmental Toxicology
- Immunology
- Molecular Biology
Background:
- 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) and related compounds induce significant immunologic effects in animals.
- These effects include reduced resistance to infections and impaired humoral and cell-mediated immunity.
- TCDD-induced immunotoxicity in mice is mediated by the aryl hydrocarbon (Ah) receptor.
Purpose of the Study:
- To elucidate the biochemical and molecular mechanisms underlying TCDD-induced immunotoxicity following Ah receptor activation.
- To investigate TCDD's role in promoting inflammatory responses, potentially via cytokine upregulation.
- To identify TCDD-sensitive immunologic biomarkers for both animal models and human subjects.
Main Methods:
- Review of existing literature on TCDD immunotoxicity in experimental animals (mice, nonhuman primates).
- Analysis of reported effects on immune responses, including antibody production and lymphocyte subsets.
- Discussion of the need for research into species differences and human exposure studies.
Main Results:
- TCDD exposure leads to decreased host resistance, suppressed immune responses, and inflammation in animal models.
- Upregulation of inflammatory cytokines like IL-1 and TNF may contribute to TCDD-induced inflammation.
- Nonhuman primates exhibit suppressed antibody responses and altered peripheral lymphocyte subsets post-TCDD exposure.
Conclusions:
- The precise molecular alterations following Ah receptor activation by TCDD remain to be fully defined.
- Characterizing TCDD's immunotoxic effects in humans requires further investigation, focusing on documented exposure.
- Establishing shared immunologic biomarkers across species is crucial for accurate risk assessment and extrapolation of findings.
