Immunotoxic effects of polychlorinated diphenyl ethers, biphenyls and dibenzofurans: Quantitative structure-activity relationships and role of the Ah receptor
The role of the aryl hydrocarbon (Ah) receptor in mediating the immunotoxic effects of several polychlorinated diphenyl ethers (PCDEs), polychlorinated biphenyls (PCBs), and alkyl-substituted polychlorinated dibenzofurans (CDFs) on the murine splenic plaque-forming cell (PFC) response to the T-cell dependent antigen, sheep red blood cells (SRBs) was investigated. The quantitative structure-immunotoxic and structure-induction activities for eight PCDE congeners were examined in C57BL/6 (Ah responsive) mice, and the results showed that the PCDEs exhibited different structure-activity relationships differing from those previously reported for the structurally-related PCBs. Four of these PCDE congeners were tested in DBA/2 (Ah non-responsive) mice, and the results showed that mechanisms other than the Ah receptor may be involved in the immunosuppression by these compounds, since certain congeners were approximately equipotent in both strains. The potencies of these PCDE congeners were compared to 2,3,7,8-TCDD and toxic equivalency factors (TEFs) were proposed. Studies of the higher chlorinated PCDEs and PCBs were also carried out in C57BL/6 mice. All of the compounds caused dose-dependent immunosuppression; however, only one of the PCDE congeners, namely 2,2[prime],3,3[prime],4,4[prime],5,6,6[prime]-nonaCDE, significantly induced high levels of hepatic microsomal ethoxyresorufin-O-deethylase activity, and none of the PCBs induced these activities at any of the doses tested. These results indicate the involvement of factors other than the Ah receptor in mediating the immunotoxic effects observed for the higher chlorinated compounds. The dose-response immunotoxic effects of the laterally-substituted PCB congeners were examined in C57BL/6 mice, and the relative immunotoxicity of these compounds was similar to their potencies for other Ah receptor-mediated responses. The immunosuppressive activity of several alkyl-substituted PCDFs was also investigated in C57BL/6 mice.
- Research Organization:
- Texas A and M Univ., College Station, TX (United States)
- OSTI ID:
- 5519704
- Country of Publication:
- United States
- Language:
- English
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560300* -- Chemicals Metabolism & Toxicology
59 BASIC BIOLOGICAL SCIENCES
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
AROMATICS
ARYL 4-MONOOXYGENASE
CHLORINATED AROMATIC HYDROCARBONS
DOSE-RESPONSE RELATIONSHIPS
ENZYMES
HALOGENATED AROMATIC HYDROCARBONS
HETEROCYCLIC COMPOUNDS
IMMUNOSUPPRESSION
ORGANIC CHLORINE COMPOUNDS
ORGANIC COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
OXIDOREDUCTASES
POLYCHLORINATED BIPHENYLS
PROTEINS
RESPONSE MODIFYING FACTORS
STRUCTURE-ACTIVITY RELATIONSHIPS
TOXICITY