Ectophospholipase A2 activity of the rabbit peritoneal neutrophil

Intact rabbit neutrophils were found to express phospholipase A2 activity against [14C]oleate-labeled autoclaved Escherichia coli. Cells obtained 12-14 h rather than 4 h after intraperitoneal injection of glycogen had approximately threefold higher activity. The higher activity was due neither to contaminating mono-nuclear cells nor to the degranulation associated with the prolonged inflammatory response in the peritoneum. Of the phospholipase A2 activity of the intact 12-hour cells, approximately one half remained cell-associated, but the other half was released from the neutrophils during incubation. The cell-associated activity was not due to phagocytosis of substrate and subsequent release of [14C]fatty acid. The cell-associated activity was inhibited by the membrane-impermeant diazonium salt of sulfanilic acid. The results indicate that the cell-associated activity of intact neutrophils is due to an ectophospholipase A2.