Identification and measurement of rat eosinophil phospholipase D. Its activity on schistosomula phospholipids

A sensitive assay, using [¹⁴C]lecithin as a substrate, has been developed for the measurement of phospholipase activity in rat peritoneal polymorphonuclear leukocytes. Cell extracts were found to contain a phospholipase D activity and indirect evidence suggested that eosinophils are responsible for the cleavage of lecithin. Intact peritoneal cells were also able to hydrolyze exogenous [¹⁴C]lecithin in vitro. When [³H]choline-labeled schistosomula were used as targets in antibody-dependent cytotoxicity experiments, the radioactivity of lecithin decreased more rapidly in a complete cytotoxicity system than in controls, suggesting that hydrolysis of schitosomula phosholipids occured during the killing process.