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(22-13) Immunotoxicological response of terrestrial and aquatic invertebrates following in vitro exposure to trace elements. Sauvé, Sébastien*,1, Fournier, Michel2, 1 Université de Montréal, Montreal, QC, Canada2 INRS-Institut Armand-Frappier-Santé humaine, Montreal, QC, Canada ABSTRACT- We tested the potential of the trace elements Ag, As, Cd, Hg, Mo, Ni, Pb, Se and Zn to inhibit the phagocytosis response of extruded coelomocytes of different worm species. We used flow cytometry to evaluate the sensitivity of cell viability and phagocytic potential for Eisenia fetida, Lumbricus terrestris, Aporrectodea turgida and Tubifex tubifex. Extruded cells were exposed 18h in vitro to concentrations ranging from 10-9 to 10-4 M. Mercury was the most potent immunotoxic element, with 50 % inhibition of phagocytosis occurring at concentrations between 10-7 and 10-6 M. Cadmium, Cu, Ni and Zn also showed significant immuno-suppressive effects with concentrations inducing 50 % inhibition ranging from 10-5 to 10-4 M. Species-specific sensitivity varied by about a factor of 10, with no species showing a systematically higher or lower in vitro sensitivity across the range of trace elements tested. We also evaluated the yield of coelomocytes and their phagocytosis potential for four different age groups of the earthworm Eisenia fetida. Cell viability was similar among size classes, cell yield increased from 0.7⋅106 per worm in the smallest class to 2.9⋅106 cells/worm in the largest class. The proportion of phagocytically active cells was lower in the smallest groups but not different among the other 3 groups. Phagocytosis increased incrementally for the first three age/weight. The absolute phagocytosis level of the hatchling worms is significantly lower than that of adult, but the inhibitory toxicity potential of incremental in vitro additions of methylmercury chloride was not different from that of adults. Key words: earthworms, trace elements, immunotoxicology, phagocytosis |
