Enhanced superoxide anion production in activated peritoneal macrophages from English sole (Pleuronectes vetulus) exposed to polycyclic aromatic compounds

As in mammals, macrophages play a vital role in the destruction of infective organisms in fish. The current study was done to determine if exposure to polycyclic aromatic compounds (PACs), a group of chemical contaminants commonly found in the sediments of urban marine areas, alters the ability of peritoneal macrophages (M[Oslash]s) from English sole (Pleuronectes vetulus) to produce cytotoxic reactive oxygen intermediates (ROIs). Initially, assay conditions including concentration of M[Oslash]s, type of in vitro stimulant, tissue culture media, and incubation time were optimized to measure production of superoxide anion (O2−), the progenitor ROI, in English sole M[Oslash]s. English sole were then injected with an organic solvent extract of a PAC-contaminated sediment equivalent to 20 g sediment (about 860 μg selected PACs) per kg fish, via their dorsal lymphatic sinus. Peritoneal M[Oslash]s were harvested on days 1, 3, 7, and 14 post-injection. Elicited peritoneal M[Oslash]s from English sole injected with the sediment extract produced significantly more O2− after stimulation in vitro with either opsonized zymosan on days 3 and 7 after exposure, or phorbol myristate acetate on day 7 when compared to the vehicle-injected or uninjected fish. Macrophages of fish injected with the vehicle responded comparably to those from uninjected individuals. No differences in the basal amounts of O2− production from activated peritoneal M[Oslash]s were observed among the treatment groups. This study demonstrates that exposure of English sole to PACs altered macrophage production of O2−. Although the direct effects of the enhanced production of this ROI are unknown, the higher levels of superoxide anion production within peritoneal macrophages may contribute to immunodysfunction and oxidative damage in P. vetulus.