Immune-associated parameters and antioxidative responses to cadmium in the freshwater crab Sinopotamon henanense

• A 21 d exposure of Cd induces physiological changes in the immune system of crab.
• Cd impairs lysosomal hemocytes in crab.
• Cd provokes immunomodulation and antioxidant defense in crab.

Cadmium (Cd) is a toxic heavy metal pollutant and is known to exert adverse effects in organisms. In this study, we examined immune-related and antioxidative parameters in crabs exposed to sublethal levels of Cd. The results showed that Cd exposure elicited a significant accumulation in hemolymph, a decrease in total hemocyte counts, and the production of reactive oxygen species (ROS). Cd treatment also upregulated activities of antioxidant enzymes including superoxide dismutase, catalase, and glutathione peroxidase in the hemocytes of crabs. Treatment with Cd further decreased the stability of lysosomal membranes in hemocytes and induced substantial changes of immune-related parameters including acid phosphatase and alkaline phosphatase. However, the activity of lysozyme varied weakly throughout the Cd treatment period. Our results suggest that Cd exposure caused immunomodulation, a potentially harmful immunity function and damage in the antioxidant system of Sinopotamon henanense.