The objective of this study was to evaluate the effect of heavy metals, at environmentally relevant concentrations, on the immune response of rainbow trout. Trout were exposed for 30 d to cadmium chloride (CdCl2), mercuric chloride (HgCl2), or zinc chloride (ZnCl2) either individually or in combinations: CdCl2/HgCl2, CdCl2/ZnCl2, HgCl2/ZnCl2, or CdCl2/HgCl2/ZnCl2. Following the 30-d exposure, p...