In vitro effects of zinc on lymphoid cells of the carp, Cyprinus carpio L.

Cells from the spleen, anterior kidney, middle kidney, thymus and peripheral blood of common carp were tested in culture at 22°C. Unlike mammals, zinc was not found to be a mitogen but to have a suppressive effect. This was usually detectable at very low concentrations (10⁻⁷M), although the degree of suppression varied depending on the organ investigated. Direct toxic effects of the metal were only observed at high concentrations (0·5 × 10⁻³ m or greater). The use of carp serum supplement rather than foetal calf serum was important in demonstrating these effects.