Effect of manganese ions on the immune response of carp (Cyprinus carpio) against Yersinia ruckeri.

The effect of manganese ions Mn2+ (Mn Cl2) on hematocrit and the antibody response of carp (Cyprinus carpio) was investigated after exposure of fish to contaminated water for 2.5 months. Contamination of water with 50 mg/l Mn2+ did not decreased antibody production against Yersinia ruckeri (measured by agglutination) but significantly decreased hematocrit. The levels of manganese in lymphoid organs (spleen and kidney) increased progressively during the experiment. The effect of manganese in vitro on phagocytosis of opsonized Yersinia ruckeri was studied by chemiluminescence. Mn2+ has a stimulating effect on phagocytosis in a range of 6.25 to 50 mg/l.