Leukotriene B4 is a potent and stereospecific stimulator of neutrophil chemotaxis and adherence.

We studied the effects of leukotrienes on in vitro functions of neutrophil polymorphonuclear (PMN) granulocytes. Leukotriene B4 (LTB4) evoked a stimulated and directed migration of neutrophils under agarose with an optimum concentration of 10(-6)M, whereas two nonenzymatically formed isomers (compounds I and II) induced this response at 10(-5)M. Leukotriene C4 (LTC4) and 5-hydroxyeicosate-traenoic acid (5-HETE) did not affect this PMN migration. At the same optimum concentrations, LTB4 and compounds I and II augmented PMN adherence to nylon fibers. The chemotactic and adherence responses were of the same magnitude as with formal-Met-Leu-Phe (fMLP) at 10(-7)M. None of the leukotrienes influenced the spontaneous or phagocytosis-associated chemiluminescence or the ability to kill Staphylococcus aures. The cyclooxygenase inhibitor, indomethacin, inhibited only partly the fMLP-induced migration at high concentrations and stimulated migration at 2.5 x 10(-7)M, suggesting that arachidonic acid was then mainly metabolized by the lipoxygenase pathways. The lipoxygenase and cyclooxygenase inhibitor, eicosatetraynoic acid, inhibited both spontaneous and stimulated migration at greater or equal to 2.5 x 10(-5)M, but not at lower concentrations. Thus, since LTB4, and to a lesser degree compounds I and II, stimulated migration and adhesion, it is suggested that these mediators could be of importance for the emigration of neutrophils from blood vessels to areas of inflammation.