The effects of heavy metals on common carp white blood cells in vitro

The in vitro effects of cadmium, copper, lead and zinc, and various cadmium compounds (chloride, sulphate and nitrate) on common carp (Cyprinus carpio) lymphocyte viability and phagocyte activity, were evaluated. The percentage of dead lymphocytes was determined after Trypan blue staining, and phagocyte activity was measured by using the nitroblue tetrazolium (NBT) reduction test. Lead was the most toxic to lymphocytes--the maximum mortality exceeded 30%, and was significantly higher at 1 microM of lead, compared to the control. The maximum mortality caused by cadmium was below 10%, but was significantly elevated with 5 microM or more of cadmium. Zinc induced lymphocyte mortality from 10 microM, whilst no effect was observed with copper. The incubation of full blood with the three cadmium compounds (at 5mg/l of cadmium) showed that cadmium nitrate and cadmium sulphate were more toxic (over 35% and 25% mortality, respectively) than cadmium chloride (about 15% mortality). This was confirmed by the results of tests on isolated cells--1mg/l of cadmium as nitrate and sulphate increased lymphocyte mortality compared to the control and cadmium chloride. Phagocytic activity was less sensitive to heavy metals than was lymphocyte viability. It was significantly reduced following exposure to 50 microM and 100 microM cadmium, and 100 microM zinc, but no effects were observed with either lead or copper.