THE EFFECT OF EICOSANOIDS ON RAINBOW-TROUT, ONCORHYNCHUS-MYKISS, LEUKOCYTE PROLIFERATION

Proliferation of rainbow trout head kidney leucocytes in response to t he mitogen phytohaemagglutinin-P (PHA-P) was modulated in the presence of inhibitors of eicosanoid synthesis and by exogenous eicosanoids. T he presence of indomethacin, a cyclooxygenase inhibitor, resulted in a stimulatory effect, whereas the presence of nordihydroguiaretic acid, a lipoxygenase inhibitor, resulted in an inhibitory effect on mitogen icity. The addition of prostaglandins and lipoxins was also found to b e inhibitory, whilst the addition of leukotrienes was stimulatory. Som e class/series effects of the eicosanoids were also apparent. Prostagl andin E(2) was a more potent inhibitor than prostaglandin E(3), and pr oliferation was more sensitive to the effects of leukotriene B-4 than to leukotriene B-5. Whilst PHA-P was able to directly induce the relea se of prostaglandins from head kidney leucocytes, it did not induce th e release of lipoxygenase products.