Metal-Induced Impairment of the Cellular Immunity of Newborn Harbor Seals (Phoca Vitulina) Antje Kakuschke Æ Elizabeth Valentine-Thon Æ Sonja Fonfara Æ Simone Griesel Æ Tanja Rosenberger Æ Ursula Siebert Æ Andreas Prange Received: 10 July 2007 / Accepted: 6 November 2007 / Published online: 1 January 2008 Ó Springer Science+Business Media, LLC 2007 Abstract The cellular immunity of newborn harbor seals and the inﬂuence of pollutants are rarely investigated. This study evaluated the lymphocyte proliferation using a lym- phocyte 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 sup- pressive effect was detected in newborns but not found in the same animals when they were older and had become immunologically competent. Summarizing, the lympho- cyte 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. Every year, many harbor seal pups (Phoca vitulina) of the Wadden Sea come ashore as a result of weakness, potential illness, weather conditions, or human interferences. Immunological defense mechanisms are very important for the survival of the pups, but the immune system is extre- mely variable and susceptible to the inﬂuence of organic pollutants in this neonatal period (Jenssen et al. 2003; Levin et al. 2005). There is, however, a lack of investiga- tion on the inﬂuence of metal pollutants. Metal exposure might result from transplacental transfer from mother to fetus or through the milk and later by contaminated prey (Itano et al. 1984; Miyazaki 1994; Storelli and Marcotri- giano 2000). Environmental pollution might affect the immunocom- petence of marine mammals and is suggested to play a role in the development of infectious diseases (Bennett et al. 2001; Jepson et al. 2005, Siebert et al. 1999). To charac- terize cellular immunity of marine mammals and/or the effects of pollutants, assays have been developed and applied to various parameters, including natural killer cell activity, phagocytosis (De Guise et al. 1995; Hammond et al. 2005; Lalancette et al. 2003; Noda et al. 2003), cytokine expression (Fonfara et al. 2007a, 2007b), and lymphocyte proliferation. The latter has been studied in different marine mammals like harbor seals (De Swart et al. 1993; Di Molfetto-Landon et al. 1995; Nielsen 1995) and various whale species (Beineke et al. 2004; Bernier et al. 2000; De Guise et al. 1996; Lahvis et al. 1995). However, only few studies dealt with seal pups (Lalancette A. Kakuschke (&)  S. Fonfara  S. Griesel  A. Prange GKSS Research Center, Institute for Coastal Research, Max- Planck-Strasse 1, 21502 Geesthacht, Germany e-mail: antje.kakuschke@gkss.de E. Valentine-Thon Department of Immunology, Laboratory Center Bremen, Friedrich-Karl-Strasse 22, 28205 Bremen, Germany S. Fonfara  U. Siebert Research and Technology Center Westcoast (FTZ), 25761 Bu ¨sum, Germany T. Rosenberger Seal Center Friedrichskoog e.V, 25718 Friedrichskoog, Germany 123 Arch Environ Contam Toxicol (2008) 55:129–136 DOI 10.1007/s00244-007-9092-3