Immunotoxic effects of copper and cadmium in the sea bass Dicentrarchus labrax

Two phagocytes-mediated activities of the sea bass Dicentrarchus labrax were examined after exposure to sublethal concentrations of copper and cadmium: (a) phagocytosis (measured by phagocytotic index), and (b) the production of reactive oxygen intermediates (luminol-dependent chemiluminescence) in response to bacteria Aeromonas salmonicida. In vivo exposure for 48 h to each metal separately by intraperitoneal injection did not affect the quantity of phagocytes of pronephros and their viability but inhibited, in dose-dependent manner, phagocytosis and chemiluminescence of these cells. The half-inhibition value was 250 micrograms kg-1 for copper and 1 mg kg-1 for cadmium. In vitro exposure to copper for 30 min had the same immunomodulatory effect on macrophage chemiluminescence as that observed in vivo, whereas treatment with cadmium under the same conditions had a dose-dependent effect opposite to that observed in vivo. Assessment of these two macrophage-mediated functions could therefore be used as early bioindicators of the marine pollution.