Human eosinophils lack human leukocyte elastase.

Recently, human leukocyte elastase has been detected in human eosinophils. Reinvestigating these findings, 2.5 pg active human leukocyte elastase (E.C. 3.4.21.37) were found per neutrophil isolated from peripheral blood, whereas the elastase activity of eosinophil preparations was linearly correlated with the content of contaminating neutrophils. Also spontaneous or stimulated release of active elastase was absent in eosinophils. By immunohistochemistry no elastase immunoreactivity could be demonstrated in human eosinophils. Therefore, we conclude that human eosinophils do not contain considerable amounts of human leukocyte elastase.