PM11 Wildlife Ecotoxicology
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(PM201) Immunomodulation in Ranch Mink (Mustela vison) Induced by Dietary Exposure to a Commercial PBDE Mixture.

Martin, P.1, Bursian, S.2, Mayne, G.1, Tomy, G.3, Palace, V.3, 1 Canadian Wildlife Service, Environment Canada, Burlington, Ontario, Canada2 Department of Animal Science, Michican State University, East Lansing, Michigan, United States3 Department of Fisheries and Oceans, Winnipeg, Manitoba, Canada

ABSTRACT- Polybrominated diphenyl ethers (PBDEs) are persistent, bioaccumulative organohalogen compounds that are increasing exponentially in certain Great Lakes biota. The present study was undertaken to investigate the immunological effects of a commercial PBDE mixture, on juvenile ranch mink. Four groups of 10 male mink were exposed to 0, 1, 5, or 10 ppm PBDE mixture through their daily diet from weaning till 17 weeks of age. The phytohemagglutinin (PHA) - induced cutaneous basophil hypersensitivity reaction, and antibodies specific to keyhole limpet hemocyanin conjugated to dinitrophenol (KLH- DNP) were measured to assess cell- and antibody-mediated immune responses. There was no difference in the PHA-induced CBH response in PBDE-exposed mink. The change in serum antibodies production was most pronounced in mink exposed to 5 ppm PBDE. While mink from all exposure groups increased their antibody production over time, the greatest percent increase was observed in mink exposed to 5 ppm and 10 ppm PBDE. Whereas mink from the control and 1 ppm exposure groups demonstrated slight increases in mass over time, body mass decreased significantly in mink exposed to 5 ppm and 10 ppm PBDE. Mink from the 10 ppm group had significantly greater relative spleen masses than control mink and on day 75, mink from the two highest exposure groups had significantly less (approximately 12%) red blood cell volume than the control and 1 ppm mink. The mechanisms of these effects are uncertain, however, our findings of immune modulation in mink are important given the complete lack of PBDE-induced immune toxicity data on animals other than laboratory rodents. It also has direct relevance to free-ranging mink in the Great Lakes ecosystem, as mink are top predators of the aquatic food web. Our results provide evidence of the vulnerability of this species to the effects of bioaccumulative PBDE compounds.

Key words: mink, PBDE, immune function

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