Phagocytic reduction and effects on lysosomal membranes by polycyclic aromatic hydrocarbons, in haemocytes of Mytilus edulis

The effects of certain polycyclic aromatic hydrocarbons (PAHs) on the immune reactivity of haemocytes from Mytilus edulis were investigated by means of a series of in vitro and in vivo experiments, utilizing phagocytosis and neutral red uptake or lysosomal neutral red retention assays. Cells in vitro were exposed to 8.3, 16.6, 25 or 50 ppm of anthracene, fluoranthene or phenanthrene, whilst whole animals were exposed to 250 mu g l(-1) (ppb) per day of single or 500 ppb double, or 750 ppb triple combinations of these PAHs. These xenobiotics were found to inhibit phagocytosis and disrupt the ability of lysosomes to take up or retain neutral red dye, suggesting that membrane permeability was affected. The differences observed in the results between the in vitro and whole animal exposure work, and between the single and combination treatments of PAHs are explained in terms of bioavailability and metabolism of the xenobiotics. The results show that PAHs have an adverse effect on cellular immune function.