KINETICS OF 5-LIPOXYGENASE ACTIVATION, ARACHIDONIC-ACID RELEASE, AND LEUKOTRIENE SYNTHESIS IN HUMAN NEUTROPHILS - EFFECTS OF GRANULOCYTE-MACROPHAGE COLONY-STIMULATING FACTOR

The kinetics of 5-lipoxygenase (5-LO) activation in human neutrophils was compared with that of arachidonic acid (AA) release and leukotriene (LT) B-4 synthesis, and the effect of granulocyte-macrophage colony-stimulating factor (GM-CSF) on these processes was examined. The soluble agonists N-formyl-Met-Leu-Phe and platelet-activating factor stimulated 5-LO activity, which peaked within 10 s and then rapidly declined. At all time points investigated, 5-LO activity was greater in GM-CSF-treated neutrophils. The release of AA was detectable only in GM-CSF-treated neutrophils and peaked 1 min after the agonist stimulation. Accordingly, synthesis of LTB(4) was detected only in GM-CSF-treated neutrophils. By comparison, 100 nM of ionomycin induced a greater and sustained activation of 5-LO, resulting in a greater synthesis of LTB(4). These results show that 5-LO activation is immediate and transient in response to soluble agonists and that temporal dissociation with the release of AA limits LTB(4) synthesis.