Effects of methyl-, phenyl-, ethylmercury and mercurychlorid on immune cells of harbor seals （Phoca vitulina）

Effects of methyl-, phenyl-, ethylmercury and mercurychlorid on immune cellsof harbor seals (Phoca vitulina)

Mercury (Hg) is present in the marine environment as a natural metal often enhanced through human activities. Depending on itschemical form, Hg can cause a wide range of immunotoxic e ects. In this study, the influence of methyl-, ethyl- and phenylmercury aswell as mercurychloride on immune functions was evaluated. Two parameters of cellular immunity, proliferation and mRNA cytokineexpression of interleukin-2, -4, and transforming growth factor , were investigated in harbor seal lymphocytes after in vitro exposureto Hg compounds. While all Hg compounds had a suppressive e ect on proliferation, di erences between juvenile and adult sealswere found. Lymphocytes from juveniles showed a higher susceptibility to the toxic e ect compared to lymphocytes from adults.Furthermore, the degree of inhibition of proliferation varied among the four Hg compounds. The organic compounds seem to bemore immunotoxic than the inorganic compound. Finally, for the cytokine expression of methylmercury-incubated lymphocytes, timedependentchanges were observed, but no dose-dependency was found. Marine mammals of the North Sea are burdened with Hg, andlymphocytes of harbor seals may be functionally impaired by this metal. The present in vitro study provides baseline information forfuture studies on the immunotoxic e ects of Hg on cellular immunity of harbor seals.