Logo: to the web site of Uppsala University

Salmon (Salmo salar) in the Baltic Sea are severly ill, showing different types of infections and increased mortality, reducing the population. The Baltic sea is heavily polluted, and one of the reason for the adverse health status of the salmon may be that halogenated chemicals in the Baltic Sea supress their immunesystem. In this study, a mixture of nine halogenated compounds (PCP, DDE, ‘PCB118, 4-OH-CB187, ‘2’-OH-BDE68, 6-OH-BDE47, 6-OHBDE90, PFOA, PFOS) that were previously detected in salmon blood serum was used to determine their impact on fish immunity. To determine the expression and function of macrophages and neutrophils after tail amputation and copper sulfate-induced inflammation, we used zebrafish (Danio rerio) embryos with fluorescently labelled cells (Tg(mpeg1:gal4-UAS:NTR-mCherry; red macrophages, and Tg(LysC:dsRED; red neutrophils). The tail regeneration assay was used to investigate if the halogenated mixture affected the regeneration ability of the zebrafish. Repressed expression of neutrophils and macrophages could be detected in zebrafish embryo from mixture exposure when inflammation was induced by copper sulfate, confirming that the mixture of halogenated chemicals containinnate immune suppressors, supporting the hypothesis that halogenated compounds found in the Baltic Sea may be an important factor underlying the adverse health effects of Baltic Sea salmon.