Immunotoxicology in wood mice along a heavy metal pollution gradient.

We carried out an immunotoxicological field study of wood mice in three populations along a heavy metal pollution gradient. Heavy metal concentrations in liver tissue indicated that exposure to silver, arsenic, cadmium, cobalt and lead decreased with increasing distance from a non-ferrous smelter. Host resistance to the endoparasite Heligmosomoides polygyrus decreased with increasing exposure, while the abundance of tick larvae and the nematode Syphacia stroma was unrelated to heavy metal exposure. Spleen mass was increased at the intermediate and the most polluted sites and was positively correlated with the number of H. polygyrus and tick larvae. Proportion of early apoptotic leukocytes increased towards the smelter and was positively related to cadmium exposure. Red and white blood cell counts and lysozyme activity showed no relationship with metal exposure. All together, our observations suggest negative effects of heavy metal exposure on the immune function of wood mice under field conditions.