Suppressive effect of turbot (Scophthalmus maximus) leucocyte-derived supernatants on macrophage and lymphocyte functions

The effect of the addition of leucocytes or leucocyte supernatants on the t urbot macrophage respiratory burst was determined. When macrophages and leu cocytes were co-incubated, the highest suppressive effect on the respirator y burst was found after 24 h. The addition of turbot leucocyte's supernatan ts from cells cultured for 17 h with culture media and foetal calf serum, t o macrophage monolayers from the same or different animals resulted, in bot h cases, in the inhibition of the macrophage respiratory burst. Leucocyte s upernatants also suppressed PKA-induced proliferation of blood lymphocytes. Inhibitors of the two main pathways of eicosanoid biosynthesis, the cycloo xygenase and lipoxygenase pathways, were also used to obtain supernatants. Although both resulting supernatants restored the macrophage respiratory bu rst activity, only cyclooxygenase derived products seemed to be implicated in the suppressive effect on macrophage respiratory burst. Nordihydroguaiar etic acid (NDGA), an inhibitor of lipoxygenase activity, was able to restor e lymphocyte proliferation to normal levels (1:2 dilution), suggesting that eicosanoids derived from lipoxygenase can be related to the inhibition of the PHA-induced proliferation. (C) 1999 Academic Press.