Oxidative damage of hepatopancreas induced by pollution depresses humoral immunity response in the freshwater crayfish Procambarus clarkii.

Previous studies provide evidences for the possible oxidative damage of toxic environmental pollutants to tissue protein in fish and amphibian, but little information is available about their effects on immunity response in crustacean. In the present study, we evaluated the relationship between oxidative damage and immune response induced by both typical pollutants (viz. copper and beta-cypermethrin), by exposing the freshwater Procambarus clarkii to sub-lethal concentrations (1/40, 1/20, 1/10 and 1/5 of the 96 h LC50) up to 96 h. Five biomarkers of oxidative stress, i.e. reactive oxygen species (ROS), superoxide dismutase (SOD), catalase (CAT), malondialdehyde (MDA) and protein carbonyl in hepatopancreas, and two immune factors, i.e. phenoloxidase (PO) and hemocyanin in haemolymph were determined. The results indicated that there was a significant increase (P < 0.05) in the contents of ROS, MDA and protein carbonyl accompanied by markedly decreased (P < 0.05) PO and hemocyanin levels in a dose and time dependent manner. The significant and positive correlation (P < 0.01) between protein carbonyls induction and MDA formation was observed in crayfish hepatopancreas at 96 h. The production of these protein carbonyls could significantly depress (P < 0.01) the levels of phenoloxidase and hemocyanin in hemolymph. Higher contents of ROS enhanced the risk of lipid peroxidation, protein carbonylation and immunosuppression of crayfish, and hepatopancreas might play an important role in immune system of crustaceans. Protein oxidation may be one of the main mechanisms for pollution-induced immunotoxicity in P. clarkii.