Metal-induced impairment of the cellular immunity of newborn harbor seals (Phoca vitulina)

The cellular immunity of newborn harbor seals and the influence of pollutants are rarely investigated. This study evaluated the lymphocyte proliferation using a lymphocyte proliferation test (LTT) to understand the dynamics of immune response in seal pups of varying ages from the moment they arrived in a seal center after active beaching until their release into wildlife 3 months later after rehabilitation. Moreover, the effect of various metals (Ag, Al, Au, Be, Cd, Co, Cr, Cu, different Hg compounds, Mo, Ni, Pb, Pd, Pt, Sn, Ti) on lymphocyte proliferation in terms of immunosuppression and hypersensitivity was investigated. First, a strong lymphocyte proliferation in newborns as a reflection of relative immunocompetence was found. Second, different metal-induced influences on lymphocyte proliferation such as specific inhibition by Be, Cd, Hg, and Sn as well as stimulation induced by Mo and Ni were determined. For seals tested repeatedly, the suppressive effect was detected in newborns but not found in the same animals when they were older and had become immunologically competent. Summarizing, the lymphocyte proliferation used as a marker in this investigation provided useful immunological information on these developing animals, and its application for toxicological studies on pollutants can be recommended.