NONSPECIFIC IMMUNE-RESPONSE OF ZEBRAFISH, BRACHYDANIO-RERIO (HAMILTON-BUCHANAN) FOLLOWING COPPER AND ZINC EXPOSURE

The cellularity of the kidney and its non-specific immune function, as assessed by macrophage phagocytosis and spontaneous natural cytotoxic ity, was studied in Brachydanio rerio kidney cells following sublethal in vivo and in vitro exposure to different copper and zinc concentrat ions. In vivo effects of heavy metals were studied in fish exposed to 0.05, 0.15 and 0.25 mg l-1 zinc and 0.05, 0.10 and 0.15 mg l-1 copper during 7 days at 22-degrees-C. Copper caused a dose-dependent decrease in the number of kidney leucocytes, NCC activity and phagocytic respo nse. Fish exposed to zinc concentrations had a lower cytotoxic activit y, an enhanced macrophage response and lower counts of kidney lymphocy tes when compared to the control group. In vitro exposure of leucocyte s to copper at 5, 10 and 20 mug ml-1 or to zinc at 10, 50 and 100 mug ml-1 for 1 h showed the same immunomodulatory effects as seen in the i n vivo exposure.