Characterizing the immunotoxicity of creosote to rainbow trout (Oncorhynchus mykiss):: a microcosm study

Several immune parameters were evaluated in rainbow trout (Oncorhynchus mykiss) after they had been exposed for 28 days in microcosms dosed initially with liquid creosote concentrations of 0, 5, 9, 17, 31, 56 and 100 mu l/l. The most noticeable changes were concentration-dependent reductions in pronephros leukocyte oxidative burst and the number of sIg(+) peripheral blood leukocytes. Plasma lysozyme levels were reduced, while pronephros leukocyte phagocytic activity was enhanced marginally across creosote concentrations. Blastogenesis in response to lipopolysaccharide (LPS) was slightly impaired in head kidney leukocyte cultures prepared from creosote-exposed fish, whereas blastogenesis in response to phytohaemagglutinin (PHA) and concanavalin-A (ConA) was unaffected. Overall the results suggest that creosote has the potential to alter some innate immune functions in rainbow trout. Polycyclic aromatic hydrocarbons (PAHs), a major constituent of liquid creosote, are the suspected immune altering agents. The LOEC of the immune responses measured in this study was 17 mu l/l using nominal creosote concentrations, representing a total PAH concentration of 611.63 ng/l in the water. (C) 1999 Elsevier Science B.V. All rights reserved.