TRANSCELLULAR METABOLISM OF LEUKOTRIENE A(4) BY RABBIT BLOOD CELLS - LACK OF RELEVANT LTC4-SYNTHASE ACTIVITY IN RABBIT PLATELETS

摘要

The objective of this study was to determine the transcellular metabolism of leukotriene A(4) by rabbit blood cells. Mixed peripheral blood leukocyte preparations with and without platelets in a ratio of 1:40 were challenged with the Ca2+-ionophore A23187. 5-Lipoxygenase metabolites production was assessed by RP-HPLC coupled with diode-array UV detection. In light of the observation that leukotriene C-4 production in leukocyte-platelet coincubation was the same as with leukocytes alone, mixed coincubation of human and rabbit blood cells was tested. Rabbit leukocytes with human platelets resulted in a significant increase of leukotriene C-4 production, while no changes were observed in human leukocytes with or without rabbit platelets. In agreement with these results, intact rabbit platelets or rabbit platelet lysates, unlike human platelets, were not able to convert synthetic leukotriene A(4) free acid to leukotriene C-4. These data provide evidence that rabbit leukocytes are able to make a significant amount of leukotriene A(4) available for transcellular metabolism, while rabbit platelets, unlike human platelets, lack leukotriene C-4-synthase activity. [References: 30]