Leukoproliferative response of splenocytes from english sole (Pleuronectes vetulus) exposed to chemical contaminants

Abstract

Abstract-The leukoproliferative (LP) response of splenic leukocytes from the marine benthic fish English sole (Pleuronectes vetulus) stimulated with the mitogens lipopolysaccharide (LPS), concanavalin A (Con A), and pokeweed mitogen (PWM) was examined as a biomarker of immunotoxic effects. English sole were exposed to contaminants, either by injection of an organic-solvent extract of a sediment containing polycyclic aromatic compounds (PACs) or placed for up to 5 weeks on a reference sediment containing 0.15 to 1.5% (v/v) of the PAC-contaminated sediment. English sole either injected with the contaminated extract or held on PAC-contaminated sediment had an augmented response to Con A. The LP response to LPS showed no relationship to PAC exposure in laboratoryexposed fish, while PWM showed no consistent relationship to exposure to PACs. In a field study, English sole captured from an urban area in Puget Sound, Washington, USA, contaminated with PACs and other chemical contaminants had a significantly augmented LP response to Con A and PWM in comparison to the LP response in fish from a nonurban reference site. Fish from another nonurban site also had an augmented LP response to Con A, indicating that the elevation of the Con A LP response can also result from factors other than chemical contaminant exposure. In addition, English sole from this site also had an augmented LP response to LPS, whereas fish from urban sites did not exhibit an augmented LP response to LPS. Overall, the results demonstrated that although the LP response in splenic leukocytes of English sole to Con A was linked to contaminant exposure, the LP response to Con A did not exhibit high specificity as an indicator of chemical contaminant exposure. However, the concerted use of Con A, LPS, and PWM allowed for identification of apparent chemical contaminant-induced alterations of the LP response in English sole from an urban area of Puget Sound.

Immunotoxicity of Xenobiotics in Fish: A Role for the Aryl Hydrocarbon Receptor (AhR)?

“…This can be explained by either suppressive effects on cell proliferation, as it has been described for B cells and innate immune cells [187][188][189]196,197], or by an increased rate of apoptosis [198][199][200]. However, some studies found either no leukocyte response [201][202][203][204], or even an increase of leukocyte proliferation under exposure to AhR ligands [182,186,196,197,[205][206][207]. Such discrepancies might be explained by species differences and/or differences in the exposure conditions.…”

“…Exposure of fish to xenobiotic AhR agonists can alter the immune cell numbers and/or proliferation [30,137,145,[186][187][188][189][190][191]. Likewise, exposure to complex environmental mixtures containing AhR ligands, such as creosote or PAH/PCB-contaminated sediments, has been found to induce alterations of immune cell numbers and ratios [29,36,[192][193][194][195].…”