Release of leukotriene C4 from human eosinophils and its relation to the cell density

Human eosinophils and neutrophils were isolated from 20 ml of peripheral blood by dextran sedimentation, centrifugation with lymphoprep, and density gradient centrifugation with Percoll. The incubation of neutrophils of purity higher than 99% (density: 1.080-1.085 g/ml) with calcium ionophore A23187 for 20 min resulted in the release of a little amount of leukotriene C4 (2.3 +/- 0.6 ng/10(6) cells) as measured with a commercial radioimmunoassay kit. On the other hand, the release from eosinophils was over 10 times that from neutrophils. When the releasability of leukotriene C4 from eosinophils was examined in relation to the cell density, the eosinophils with lower density were observed to produce greater amounts of leukotriene C4.