PCBs increase molecular-related activities (lysozyme, antibacterial, hemolysis, proteases) but inhibit macrophage-related functions (phagocytosis, wound healing) in earthworms.

Both humoral and cellular immunodefense responses of the earthworms, Eisenia fetida andrei, Eisenia hortensis, and Lumbricus terrestris, have been compared after exposure to the PCB Aroclor 1254. Responses mediated by free factors, detected by in vitro assays for lysozyme, hemolysis, and proteases, were increased in both Eisenia. Antibacterial activity directed against pathogenic bacteria was increased in E.f. andrei. The resistance of L. terrestris against non-pathogenic bacteria was decreased, confirming that the bacteria were treated by different systems according to their pathogenicity. Nonspecific cellular functions, including phagocytosis and those related to wound healing, decreased dramatically in all earthworms.