INTRINSIC 5-LIPOXYGENASE ACTIVITY IS REQUIRED FOR NEUTROPHIL RESPONSIVITY

We found that intrinsic neutrophil 5-lipoxygenase activity was necessary for human neutrophil adherence and chemotaxis in vitro and human neutrophil-mediated acute edematous injury in isolated perfused rat lungs given interleukin 8 intratracheally. Treatment with either Zileuton (a specific reversible competitive inhibitor of 5-lipoxygenase) or MK886 (a specific irreversible inhibitor of the 5-lipoxygenase activator protein) prevented stimulated neutrophil adherence and chemotaxis (but not superoxide anion production) in vitro. Zileuton- or MK886 inhibited neutrophil chemotaxis was not restored by adding leukotriene B-4 in vitro. Perfusion with neutrophils and either Zileuton or MK886, or with MK886-pretreated neutrophils (without adding MK886 to the perfusate), also prevented lung injury (reflected by lung weight gain and lung Ficoll retention) and perfusate leukotriene B-4 increases in isolated rat lungs given interleukin 8 intratracheally. Again, adding leukotriene B-4 to the perfusate did not damage interleukin 8-treated isolated lungs perfused with Zileuton-inhibited neutrophils. We conclude that intrinsic 5-lipoxygenase activity is required for neutrophil adherence and chemotaxis and neutrophil-mediated lung injury.