EFFECTS OF 4-NONYLPHENOL ON THE IMMUNE SYSTEM OF RAINBOW TROUT (Oncorhynchus mykiss)

Alkylphenol polyethoxylates are widely used as surfactants and find their way in urban wastewaters. Nonylphenol (NP) is a degradation product of these surfactants and contaminates also the aquatic biota. NP is clearly recognized as an estrogen but research focusing on the impacts of the immune system in fish is scarce. Our study therefore sought to investigate the effects of NP in juvenile rainbow trout (Oncorhynchus mykiss) on the immune system at the level of phagocytosis, lymphocyte B and T proliferation, as well as natural cytotoxic cell (NCC) activity. After 54 days of exposure to NP, trout showed a significant decrease of active phagocytic activity. NCC activity was significantly enhanced at 54 days when compared to controls. A moderate decrease in [H-3]-thymidine DNA incorporation was observed for T and B lymphocyte. These results suggest that NP can affect the immune system in juvenile rainbow trout at environmental levels thought to be safe for aquatic species.