Abstract
Leukotrienes (LTs) producing capacity was investigated in calcium ionophore A23 187- stimulated rabbit. rat and mice peripheral white blood cells suspension. A reverse phase high performance liquid chromatography technique and computerized UV spectroscopy were employed to isolate and quantitate the released LTs namely. LTC4 and LTB4. Preincubation of rabbit white blood cells at 37°C for 5 min followed by calcium ionophore-A23 187 (1 pM) stimulation for another 5 min produced an equal amounts of LTC4 as compared to LTC4 produced by human white blood cells (105±11 versus 95±9.5 pmol/107 cells respectively; mean ±SEM). In contrast rabbit white blood cells synthesized significantly lower LTB4 in comparison with LTB4 produced by peripheral white blood cells from healthy control (168±18 versus 228±19 pmol/107 cells respectively: mean ±SEM). When rat and mice white blood cells suspension were stimulated with calcium ionophore A23187 (1 µM) after preincubation at 37°C for 5 min, equivalent amounts of LTC4 and LTB4 were observed. However, LTB4 and LTC4 produced by rat and mice white blood cells were significantly lower in comparison with LTB4 and LTCj produced by human white blood cells stimulated with calcium ionophore-A23 187. These results demonstrate that rabbit. rat and mice white blood cells suspension possess the capacity to produce LTC4 and LTB4 from endogenous substrate after calcium ionophore-A23 187 stimulation.
Highlights
Leukotrienes (LTs) producing capacity was investigated in calcium ionophore A23 187stimulated rabbit. rat and mice peripheral white blood cells suspension
I~n.various human cell types and tissues, leukotriene Aq is metabolized via three main pathways; by cytosolic LTAq hydrolase (EC 3.3.2.6) to the potent leukocyte activator, LTB~'or by membrane bound LTC4 synthase (EC 2.5.13 7 ) to the spasmogenic cysteinyl containing leukotriene vir L T C ~ 'or spontaneously non-enzymaticaly hydrolysed to the biologically inactive stereoisomers namely; 6-trans LTB4 and 12-epi-6trans L T B ~ ~En. dogenous and exogenous stimuli including platelet activating factor, chemotactic peptide C5a and calcium ionophore A23187 have been shown to trigger the release of LTS"
Rabbit white blood cells produced an equivalent amount of LTC, as compared to that produced by peripheral white blood cell
Summary
Leukotrienes (LTs) producing capacity was investigated in calcium ionophore A23 187stimulated rabbit. rat and mice peripheral white blood cells suspension. LTB4 and LTC4 produced by rat and mice white blood cells were significantly lower in comparison with LTB4 and LTCj produced by human white blood cells stimulated with calcium ionophore-A23 187. LTC4 once formed is exported from the cells via an active transport to the extra-cellular space1'.The subsequent conversion of LTC4 into LTDd via removal of y -glutamyl moiety from glutathione is catalyzed by y-glutamyl-transpepetidase, an enzyme located at the external site of plasma membranet2 This reaction can not be considered as biological inactivation. These effects reflect an ability to accentuate free radicals generation and indicating an ability to augment and prolong tissue inflammation
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