Phagocytic Response of Terrestrial and Aquatic Invertebrates Following in Vitro Exposure to Trace Elements

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 was tested. 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 18 h in vitro to concentrations ranging from 10−9 to 10−4M. Mercury was the most potent immunotoxic element, with 50% inhibition of phagocytosis occuring at concentrations between 10−7 and 10−6 M. Cadmium, Cu, Ni, and Zn also showed significant immunosuppressive 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.