Studies on leukotriene B4 ω-oxidation in human leukocytes

Abstract

The kinetics of the transformation of arachidonic acid into 5-lipoxygenase products in human blood leukocytes stimulated with the ionophore A23187 (2 μM) was studied using high performance liquid chromatography. The levels of 5-hydroxyeicosatetraenoic acid (5-HETE), leukotriene B4 (LTB4), Δ6-trans-UTB4, and leukotriene C4 (LTC4) were maximum after 4–5 min of incubation; at longer incubation times, the levels of Δ6-trans-LTB4 and LTC4 remained unchanged, whereas those of 5-HETE and LTB4 decreased rapidly. The disappearance of LTB4 was concomitant with the formation of ω-hydroxy-LTB4 and ω-carboxy-LTB4. When synthetic LTB4 was added to a suspension of unstimulated human leukocytes, a similar pattern of ω-oxidation products was observed. This ω-oxidation process showed some specificity for LTB4, as indicated by the slower reaction of three stereoisomers of LTB4. Studies with subpopulations of human blood cells and human plasma clearly indicated that the polymorphonuclear leukocytes were the main source of enzymic activity for the ω-oxidation of LTB4. The liquid chromatographic behaviors of natural ω-hydroxy-LTB4 and ω-carboxy-LTB4 were studied in two systems.