PARENT SESSION

PW08 Aquatic Ecotoxicology II
Exhibit Hall
8:00 AM - Wednesday

(PW130) Toxic Effects of Great Lakes Contaminants on Lake Trout Immune Cells.

Passino-Reader, D¹, Benitez, M¹, Sweet, L², Miller, G², Birchmeier, K², Smith, K², Adams, J³, Meier, P², Omann, G⁴, ¹ USGS Great Lakes Science Center, Ann Arbor, MI, USA² Environ. Health Sci., Sch. Public Health, Univ. of Michigan, Ann Arbor, MI, USA³ USGS Great Lakes Science Center, Marquette, MI, USA⁴ Medical School, Univ. of Michigan, and VA Medical Center, Ann Arbor, MI, USA

ABSTRACT- Lake trout (Salvelinus namaycush) a sentinel species of ecosystem health in the Great Lakes are exposed to a wide array of toxic chemicals. Aquatic contaminants in the Laurentian Great Lakes and elsewhere have been implicated in altering the physiology of ecological and human biota. From several studies on vertebrate species, certain chemical species are suspected of modulating immune system function via suppression and inhibition of immune competence, stimulation and hypersensitivity, autoimmunity and toxicity. The thymus is believed to be a central component of haematopoiesis and immune function in lake trout and other teleosts. The objectives of this research were to assess the levels of active (apoptotic) and passive (necrotic) cell death in untreated and contaminant treated fish thymocytes, as a endpoint in immune functioning. Thymocytes isolated from cultured lake trout were exposed in vitro under predetermined conditions of temperature and time to selected heavy metals and organohalides. The environmental contaminants investigated were mercury (as HgCl ₂), polychlorinated biphenyls (PCBs, as Aroclor 1254), polybrominated diphenyl ethers (PBDEs, as congeners BDE47, BDE99, LMS mixture), and hexachlorocyclohexane (as -, -, -, and - HCH isomers). Additionally, toxicity and interactions between the contaminants and immunomodulatory agents (lipopolysaccharide and cortisol) on the thymocytes were determined with in vitro assays. The resulting viability, apoptosis, or necrosis of the thymocytes was assessed with cytofluorometry confirmed with fluorescence microscopy. This research demonstrated that the effects of exposure time, temperature, concentration levels and specific chemical species may compromise immune cell response. Aroclor 1254 and mercury were toxic at ambient concentrations but PBDEs were not. Significant interaction occurred between Aroclor 1254 (or HgCl₂) and cortisol, but not lipopolysaccharide (bacterial endotoxin). The toxicity of these contaminants to thymocytes poses a risk for increased vulnerability to and duration of infections from pathogens in lake trout.

Key words: pcb, pbde, thymocyte, lake trout