GENERATION OF LEUKOTRIENE B4, ITS ALL trans ISOMERS AND 5-HYDROXYEICOSATETRAENOIC ACID BY RAT BASOPHILIC LEUKAEMIA CELLS

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Abstract
1 When rat basophilic leukaemia (RBL-1) cells were incubated for 4 min, in the presence of arachidonic acid (AA) and calcium ionophore A23187, three isomers of leukotriene (LT) B4 and 5-hydroxyeicosatetraenoic acid (5-HETE) were generated. 2 The isomers of LTB4 separated by reverse phase high pressure liquid chromatography (h.p.l.c.) were found to be 5(S),12(S)-dihydroxy-6,14-trans-8,10-trans-eicosatetraenoic acid; 5(S), 12(R)-dihydroxy-6,14-trans-8,10-trans-eicosatetraenoic acid and 5(S),12(R)-dihydroxy-6,14-cis-8,10-trans-eicosatetraenoic acid or LTB4. 3 5(S), 12(R)-cis, trans, trans-LTB4 produced by RBL-1 cells caused aggregation of rat polymorphonuclear leucocytes (PMNs). Its other two isomers (5(S), 12(S)-all trans-LTB4; 5(S),12(R)-all trans-LTB4) were much less active and 5-HETE was found to be inactive. 4 5(S),12(R)-cis, trans, trans-LTB4 formed from RBL-1 cells contracted guinea-pig parenchymal strips (GPPs) and was indistinguishable from synthetic 5(S),12(R)-cis, trans, trans-LTB4. The other two isomers of LTB4, i.e. 5(S),12(S)-all trans-LTB4 and 5(S),12(R)-all trans-LTB4 as well as 5-HETE were inactive on GPP. 5 RBL-1 LTB4 was equipotent with LTD4, in most experiments, in contracting GPP but had no activity on guinea-pig ileum smooth muscle (GPISM). 6 RBL-1 cells contain the enzyme systems necessary for generating LTB4 as well as the leukotriene(s) with amino acid residues at C-6.