Effects of metals on the chemiluminescent response of rainbow trout (Salmo gairdneri) phagocytes.

Quantification of an induced chemiluminescent (CL) response in phagocytes is currently being evaluated as an indicator system for determining those environmental pollutants that may predispose fish to disease. A CL assay was developed using phagocytes from the pronephros of rainbow trout (Salmo gairdneri). The CL response of phagocytes to phorbol myristate acetate, a chemical inducer of CL, was shown to be dose-dependent. The response to five species of bacteria was also evaluated. Staphylococcus aureus and Aeromonas hydrophila produced the most intense CL responses and the longest duration of response (100 min.) Yersinia ruckeri induced an immediate strong CL response of short duration (20 min.) whereas Vibrio anguillarum and Aerococcus viridans failed to stimulate CL under the test conditions employed. The effect of sub-toxic levels of Cu, Al, and Cd on the CL response of phagocytes to S. aureus was examined using phagocytes exposed to the metals immediately before assay or after 1 hr or 24 hr exposure times. Copper caused a significant decrease in CL to the baseline level under all treatment conditions upon stimulation with S. aureus. Similar results were obtained with Al except that the decrease in CL, although significant, was not to the baseline level. In contrast, Cd caused a significant increase in CL when added 1 hr prior to or immediately before the assay; but, following a 24 hr exposure, the results were variable, in that either no change or a decrease was observed. The addition of Cu to phagocytes already exhibiting a strong CL response to S. aureus caused an immediate decrease in CL to that seen with the negative controls.