IN-VITRO MERCURY-RELATED CYTOTOXICITY AND FUNCTIONAL IMPAIRMENT OF THE IMMUNE CELLS OF RAINBOW-TROUT (ONCORHYNCHUS-MYKISS)

Cytotoxic and immunotoxic effects of mercury chloride and methylmercur y on blood and head kidney leucocytes of rainbow trout (Oncorhynchus m ykiss) were evaluated in vitro, for a broad dose range (10(-4)-10(-9) M Hg) of the chemicals. Mercury-related impairment of functional cellu lar parameters were measured using mixed leucocyte reaction (MLR) and mitogen stimulation of the cells by phytohaemagglutinin (PHA), concana valin A (Con A) and lipopolysaccharide (LPS). Non-specific defense mec hanisms of blood neutrophils and pronephros macrophages were analysed using flow cytometric assay of phagocytosis and respiratory burst. Imp airment of the functional cellular activities appeared to be limited a lmost exclusively to cytotoxic concentrations of the mercurials. Simil arly, phagocytic and respiratory burst activities of blood and head ki dney phagocytes were markedly impaired by high, cytotoxic concentratio ns of the mercurials. The in vitro cytotoxic potential of methylmercur y; greater-than-or-equal-to 10(-5) M Hg, appeared to be at least ten t imes higher over the cytotoxicity of mercury chloride greater-than-or- equal-to 10(-4) M Hg. At lower mercury concentrations, the data showed mostly normal- or above-normal values of the assayed functional activ ities of the cells. Overall, a nonspecific, poisoning-related impairme nt of leucocyte and phagocyte functions was concluded for the in vitro cytotoxic concentrations of mercurials.