Oxidative responses in ferret macrophages

Although the basic function of T and B lymphocytes in ferrets has been known for some time, the function of mononuclear phagocytes has not been described in this species. The present study has characterised basic oxidative responses in ferret macrophages, and has investigated the effects of endogenous and exogenous modulators of macrophage function on oxidative capacity in vitro. Macrophages derived from the blood or lungs of ferrets were shown capable of generating the reactive oxygen intermediate (ROI) molecules superoxide and hydrogen peroxide, and secreting a lysosomal enzyme (acid phosphatase), in response to appropriate stimuli. A T cell supernatant (derived from mitogen-stimulated peripheral blood lymphocytes) was able to activate both blood- and lung-derived macrophages for enhanced ROI production, while specific ROI inhibitors (superoxide dismutase and catalase) were able to partially ablate ROI activity. The accumulation of nitrite in culture supernatants, as an indicator for the production of reactive nitrogen intermediates, could not be demonstrated by ferret macrophages derived from either tissue source. In contrast to the enhancing effects of TCS on the oxidative function of blood-derived macrophages, exposure to bacterial LPS caused marked suppression of ROI and lysosomal enzyme production by these cells. Finally, the generation of superoxide anion, following phagocytosis of live or heat-killed Mycobacterium bovis or zymosan, indicated that ROI production in response to phagocytic stimulation was relatively weak in ferret blood-derived macrophages. These results are discussed in relation to the study of immune function in a novel species, and with particular reference to research into tuberculosis (Tb), since ferrets are important wildlife vectors of bovine Tb in New Zealand.