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(640) Mixtures of 17-beta estradiol and benzo-a-pyrene stimulate phagocyte activities and suppress secondary antibody responses in channel catfish, Ictalurus punctatus.
Frederick, Lee*,1, Karsten, Amanda1, Rice, Charles1, 1 Clemson University, Clemson, SC, USA
ABSTRACT- Benzo-a-pyrene (BAP) is considered to be highly immunotoxic in fish following sediment exposures and intraperitoneal injections. The immunotoxic potential of BAP in fish following dietary exposures is unknown. Likewise, little is known about the immunotoxic potential of dietary xenoestrogens in aquatic organisms. Theoretically, very low doses of estradiol (E2) should be as immunomodulating as very high levels of xenoestrogens. We exposed channel catfish to dietary BAP and E2 (1 and 100 ppb each) alone, and as mixtures over a 49 day period. Fish were immunized i.p. with Vibrio anguillarum or bovine gamma globulin (BGG) on day 7 of the feeding study, and again on day 28. Immune function and plasma vitellogenin levels were then measured on days 7, 28, and 49 during exposures. Primary antibody responses to V. anguillarum (a particulate immunogen) and BGG (a soluble immunogen) were enhanced by both E2 and BAP. Secondary antibody responses to both immunogens were inhibited. Phagocyte oxidative burst activities were enhanced by E2, but unaltered by BAP or mixtures of BAP and E2. No interactive effects of BAP and E2 on immune functions were observed. Despite the potent effects of E2 on immune function, treatments did not induce vitellogenesis as measured by ELISA using newly developed mAbs specific for channel catfish vitellogenin. This study indicates that low levels of dietary xenoestrogens may target the immune system of fish before altering their reproductive physiology.
Key words: Fish, Immunotoxicity, PAHs, Estrogens
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