5-Lipoxygenase activity in the human pancreas.

Low levels of 5-lipoxygenase (5-LO), the first committed enzyme in the synthesis of leukotrienes (LTs), have been reported in the porcine pancreas. We have quantitated 5-LO activity in subcellular fractions of pancreas samples from three human donors. 5-LO activity was detectable in all samples, although enzyme activity was lower than in human leukocytes. 5-LO in human pancreas samples displayed highest specific activity in membrane fractions, and did not require arachidonic acid (AA) addition for activity. These unusual characteristics of pancreatic 5-LO appear to be due, at least in part, to the presence of unesterified AA in the pancreas samples. Western blot analysis demonstrated that the human pancreas contains low levels of 5-lipoxygenase-activating protein (FLAP) in addition to 5-LO.