Cadmium exposure of rainbow trout, <i>Salmo gairdneri</i> Richardson: effects on immune functions

Abstract

Differential leucocyte counts, phagocytosis, humoral antibody response and the in vitro blasto‐genetic response to mitogens (lipopolysaccharide and Concanavalin A) and to an antigen ( Vibrio anguillarum ) were studied in rainbow trout exposed to 0,0.7 or 3.6 μg Cd 1 −1 for 12 weeks. Although the fish did not exhibit any clinical or histological changes, cadmium exposure was found to affect two of the immune parameters measured. The cellular response of fish immunized with V. anguillarum to the homologous antigen was significantly lower for splenocytes obtained from fish exposed to cadmium for 9 weeks (3.6 μg Cd 1 −1 group) than for splenocytes obtained from non‐exposed fish. Conversely, the humoral antibody response to V. anguillarum O‐antigen was higher in the 3.6 μg Cd 1 −1 group than in the non‐exposed group. Protective immunity of fish vaccinated against V. anguillarum was equally as good in the cadmium‐exposed group as in the non‐exposed group. No cadmium‐induced changes in differential leucocyte counts or in the proportions of phagocytic cells were observed.