The influence of heavy metal emissions and Fasciola hepatica infestation on the immunogenicity of a Listeria vaccine.

The effect of oral dosing with emissions containing heavy metals (mercury, lead, copper, cadmium, zinc and chromium) on immune status was tested in 3 groups of sheep. Two groups (Groups I and II) were given emissions for 15 d. One of these groups (Group I) was then also infested with Fasciola hepatica metacercaria on day 16. These 2 groups (Groups I and II) and a control group (Group C) were immunized with a Listeria vaccine on days 8 and 22. A decreased index of metabolic response (IMR) of phagocytes and reduced responses of lymphocytes to mitogenic activation with phytohemagglutinin and L monocytogenes antigen stimulation in the leukocyte migration-inhibition test were recorded. Decreased agglutination titers of serum antibodies against L monocytogenes were observed. The F hepatica infestation had no significant effect on the migration index or IMR.