PARENT SESSION

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

(PW127) Immunotoxicity and CYP1A1 expression in two populations of Atlantic tomcod exposed to PCB 126.

Berg, E¹, Wirgin, I¹, Roy, N¹, Duffy, J¹, Carlson, E¹, Zelikoff, J¹, ¹ New York University School of Medicine, Tuxedo, NY, USA

ABSTRACT- The Hudson River (HR) estuary (NY) is severely polluted with polychlorinated biphenyls (PCBs), contaminants known to bioaccumulate in wildlife species, and alter immune function in both fish and mammals. Resistance to PCB-mediated cytochrome P4501A1 (CYP1A1) induction has been previously observed in Atlantic tomcod (Microgadus tomcod) from the HR. The current study seeks to determine the effects of PCB 126 on the nonspecific immune response of laboratory-reared Atlantic tomcod bred from fish captured in either the PCB-contaminated HR or the Miramichi River (MR) reference site, as well as to explore the role of CYP1A1-resistance in PCB-mediated immunotoxicity. Fish, injected i.p. with either the vehicle control, 0.01, 0.1 or 1.0 ug PCB 126 / g BW, were examined after 7 and 14 days. Intra- and extracellular superoxide (O₂^.-) production, phagocytic activity, and activation of the alternative complement pathway were evaluated as measures of nonspecific immunity. Hepatic CYP1A1 mRNA induction in both populations was also determined. Extracellular O₂^.- production was decreased after 7 days in HR fish exposed to 1.0 ug/g PCB (compared to controls). After 7 days, phagocytosis was depressed in MR tomcod exposed to the highest PCB dose (compared to controls); alternatively, HR fish exposed to the same PCB concentration demonstrated elevated activity after 14 days. Alternative complement activity was decreased after 7 days in HR tomcod exposed to 1.0 ug PCB 126/ g BW. CYP1A1 was induced after both 7 and 14 days in PCB-exposed MR fish, but not in HR-derived fish. Results from this study suggest that PCB-induced immunotoxicity in M. tomcod may be mediated by a mechanism other than CYP1A1 metabolism. NIEHS Center Grant ES00260 and DOD DAMD 17-99-2-9011.

Key words: Fish, Immunotoxicology, Polychlorinated biphenyl, Hudson River