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(70-81) Contrasting changes of sensitivity to mercury of lymphocytes and neutrophiles in developing grey seal. Fournier, M.*,1, Lalancette, A.1, Morin, Y.1, Measures, L.2, Fortier, M.1, Brousseau, P.1, 1 INRS-Institut-Armand-Frappier, Pointe-Claire, Québec, Canada2 Institut Maurice-Lamontagne, Fisheries and oceans canada, Mont-Joli, Québec, Canada ABSTRACT- Mercury is the principal metal contaminant in the St. Lawrence Estuary. It impairs humoral, cellular and non-specific immune responses in many species. Since the immune system of juvenile seals is developing, it should be more sensitive to the effects of contamination than of mature animals. Phagocytosis and lymphoblastic transformation responses have been evaluated in the peripheral blood leukocytes (PBL) of eight juvenile grey seals at different timepoints for a period of 11 weeks. Also, dose-responses curves of 10-3 to 10-9 M of methylmercury chloride have been performed in vitro for the evaluation of these two immune functions. The immune response of grey seals is different during their development. The phagocytosis response increased from the 2nd to 5th week after weaning and then reached a plateau. As for the lymphoblastic transformation response, it was stable from the 2nd to the 3rd week postweaning, increased significantly at week 4 and then reached a plateau. Furthermore, mercury decreased the immune response and interacted with the age factor. Concentrations from 10-5 to 10-6 M of methylmercury chloride decreased the phagocytosis and the lymphoblastic transformation responses. The two immune functions studied in the St. Lawrence juvenile grey seals are more sensitive to the effects of contamination before their full development. Consequently, these animals should be particularly vulnerable to infections, diseases and parasites before the 5th week postweaning. Key words: Mercury, Immunotoxicology, Seals |
