Leukotriene B4 -LTB4) is a dihydroxy fatty acid derived from arachidonic acid through the 5-LO pathway. It promotes a number of leukocyte functions including aggregation, stimulation of ion fluxes, enhancement of lysosomal enzyme release, superoxide anion production, chemotaxis, and chemokinesis. In subnanomolar ranges -3.9 x 10^-10 M), LTB4 causes chemotaxis and chemokinesis in human polymorphonuclear leukocytes. At higher concentrations, -1.0 x 10^-7 M), LTB4 leads to neutrophil aggregation and degranulation as well as superoxide anion production.