TWENTY-FOURTH ANNUAL EASTERN FISH HEALTH WORKSHOP Royal Pavilion Resort, Atlantic Beach, NC MARCH 9-11, 1999 Environmental Metals May Activate Inappropriate Growth And Differentation In Teleost Peripheral Blood Leukocytes Through The Extracellular Related Kinase (ERK) Pathway Karen G. Burnett, A. Karlsson and K. Kohlberg Department of Microbiology and Immunology, Medical University of South Carolina, Charleston, SC Environmental stressors, including metal and organic compounds as well as natural environmental variables, such as temperature, pH and oxygen, can dramatically alter resistance to infectious disease in aquacultured species. In mammalian cell lines and primary cell cultures the balance among intracellular signaling pathways, in particular the mitogen activated protein kinase pathways (MAPKs) ultimately may determine whether an antigen elicits an immunogenic or toleratogenic response. Environmental chemicals which alter the activity of these MAPKs may interfere with normal mechanisms of disease resistance. Teleost lymphocytes possess a least one of the MAPKs, the extracellular-related kinase pathway (ERK). Activation of mammalians ERKs is directly correlated with cell growth. Using Western blots with an antibody to activated mammalian ERKs we monitored the responses of freshly isolated teleost peripheral blood lymphocytes (PBL) to several metals which are commonly detected in natural aquatic environments. A 15 minute exposure to lead, aluminum, chromium, copper and uranium activated ERKs in PBL of the marine red drum, Sciaenops ocellatus, while cadmium, zinc and nickel had no effect on this pathway. Only lead and aluminum activated ERKs in channel catfish, Ictalurus punctatus, PBL These results suggest that common environmental metals may inappropriately modulate the immune response in teleost PBL by stimulating rather than suppressing cell growth or differentiation. The underlying mechanism for these effects and the outcome of exposure to metal mixtures is currently under investigation. Supported by DOE Cooperative Agreement DE-FC02-98CH10902. Return to 24th Annual Eastern Fish Health Workshop Return to Leetown Science Center Home Page