Relationships between in vitro lymphoproliferative responses and levels of contaminants in blood of free-ranging adult harbour seals (Phoca vitulina) from the North Sea

Abstract

In vitro culture of peripheral blood leucocytes (PBLs) is currently used in toxicological studies of marine mammals. However, blood cells of wild individuals are exposed in vivo to environmental contaminants before being isolated and exposed to contaminants in vitro. The aim of this study was to highlight potential relationships between blood contaminant levels and in vitro peripheral blood lymphocyte proliferation in free-ranging adult harbour seals (Phoca vitulina) from the North Sea. Blood samples of 18 individuals were analyzed for trace elements (Fe, Zn, Se, Cu, Hg, Pb, Cd) and persistent organic contaminants and metabolites (ΣPCBs, ΣHO-PCBs, ΣPBDEs, 2-MeO-BDE68 and 6-MeO-BDE47, ΣDDXs, hexachlorobenzene, oxychlordane, trans-nonachlor, pentachlorophenol and tribromoanisole). The same samples were used to determine the haematology profiles, cell numbers and viability, as well as the in vitro ConA-induced lymphocyte proliferation expressed as a stimulation index (SI). Correlation tests (Bravais-Pearson) and Principal Component Analysis with multiple regression revealed no statistically significant relationship between the lymphocyte SI and the contaminants studied. However, the number of lymphocytes per millilitre of whole blood appeared to be negatively correlated to pentachlorophenol (r=-0.63, p=0.005). In adult harbour seals, the interindividual variations of in vitro lymphocyte proliferation did not appear to be directly linked to pollutant levels present in the blood, and it is likely that other factors such as age, life history, or physiological parameters have an influence. In a general manner, experiments with in vitro immune cell cultures of wild marine mammals should be designed so as to minimize confounding factors in which case they remain a valuable tool to study pollutant effects in vitro.

Immunomodulatory effects of exposure to polychlorinated biphenyls and perfluoroalkyl acids in East Greenland ringed seals (Pusa hispida)

“…antibody production) in experimentally exposed mink (Martin et al, 2007). To date, relationships between HCB and changes in marine mammal immune functions have not been documented (Dupont et al, 2013).…”

Essential and Toxic Elements in Blood Samples of Harbor Seals (Phoca vitulina) from the Islands Helgoland (North Sea) and Anholt (Baltic Sea): A Comparison Study with Urbanized Areas

“…The animals from both studies were within the same age group ([2 years). Due to the fact that no gender-related differences had been found in former studies (Griesel et al 2008;Dupont et al 2013), the results for males and females were pooled. The results from Anholt seals were not statistically tested due to the small number and different age of animals.…”

“…Blood sampling of harbor seals is considered minimally invasive and allows the analyses of pollutants, biomarkers, and health parameters additionally to in vitro cell experiments from living animals. For the North Sea, several investigations have been performed to measure contaminants (Griesel et al 2006;Das et al 2008;Griesel et al 2008;Kakuschke et al 2009;Weijs et al 2009a, b, c;Kakuschke et al 2010b), assess immune cell functions (De Swart 1995;Ross 1995;Kakuschke et al 2005;Das et al 2008;Dupont et al 2013), or analyse biomarkers Hasselmeier et al 2008;Kakuschke et al 2010a;Grebe et al 2010Grebe et al , 2011Grebe et al , 2012Kakuschke et al 2013) in blood samples of harbor seals. Most of these studies focused on animals closed to urbanized areas along the Wadden Sea coast.…”

Toxicology of Marine Mammals: New Developments and Opportunities

“…Nevertheless, there are also studies reporting immunotoxicity in relation to heavy metal exposure (e.g. Camara Pellissó et al 2008;Dupont et al 2013). Studies on wild individuals have been extensively performed in seals, which are somewhat easier to capture with respect to cetaceans, allowing sampling (blood, skin, etc.)…”

“…for in vitro studies (e.g. Mori et al 2006;Das et al 2008;Frouin et al 2008;Kakuschke et al 2011;Dupont et al 2013).…”