In vitro exposure of seal peripheral blood leukocytes to different metals reveal a sex-dependent effect of zinc on phagocytic activity

• Published in: Marine Pollution Bulletin
• Main Authors: Pillet, S., Lesage, V., Hammill, M., Cyr, D.G., Bouquegneau, J.-M., Fournier, M.
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2000
• Subjects: Halichoerus grypus; Phoca vitulina
• Online Access: http://www.vliz.be/nl/open-marien-archief?module=ref&refid=32418

Although the immunotoxicity of heavy metals is well established, evaluation of their potential immunotoxicity in wildlife species is complicated by variables that could modulate the immune response to xenobiotics under field conditions. Phagocytosis plays a key role in the mammalian immune response. The objectives of our study were to develop a method for measuring the phagocytic activity of seal peripheral blood granulocytes, and to determine the effects of both zinc chloride (ZnCl 2 ), cadmium chloride (CdCl 2 ) and mercuric chloride (HgCl 2 ) on this immune function of peripheral blood granulocytes in vitro . Peripheral blood leukocytes (PBLs) were isolated from the peripheral blood of either harbour seals ( Phoca vitulina ) or grey seals ( Halichoerus grypus ) captured in the St Lawrence Estuary. Cells exposed for 4 h to 10 -4 M and 10 -3 M HgCl 2 displayed lower phagocytic activity but this was related to a general cytotoxic effect of HgCl 2 as opposed to a specific effect on phagocytosis. Exposure of PBLs from either male or female PBLs to CdCl 2 had no effect on phagocytic activity at the concentrations tested except a significant decrease in cells from male harbour seals exposed to 10 -4 M. Exposure to ZnCl 2 at physiologically relevant concentrations enhanced the phagocytic activity of PBLs from mature females of both species, whereas no effect was observed in cells from either males or immature females. In conclusion, we have developed an in vitro assay to test the effects of environmental contaminants on the phagocytic activity of seal PBLs. Our data indicate that exposure of PBLs to ZnCl 2 results in a sex-dependent response and that PBLs from mature female seals are more sensitive to ZnCl 2 than either male or immature seals. This sex-dependent response to ZnCl 2 could lead to a differential sensitivity to heavy metal exposures for males and females seals in the field.