CYTOKINE INDUCTION OF GRANULE PROTEIN-SYNTHESIS IN AN EOSINOPHIL-INDUCIBLE HUMAN MYELOID CELL-LINE, AML14

Study of eosinophil growth and differentiation has been hampered by th e difficulty of obtaining adequate numbers of highly purified eosinoph il progenitors or mature eosinophils for analysis. The AML14 myeloid l eukemia cell line has the unusual ability to exhibit eosinophilic diff erentiation in response to stimulation by combinations of the eosinoph il-active cytokines interleukin-3 (IL-3), granulocyte-macrophage colon y-stimulating factor, and IL-5. We now demonstrate that AML14 cells ca n be stimulated by a combination of these cytokines to produce mRNA en coding all the eosinophil granule proteins, including major basic prot ein (MBP), eosinophil peroxidase (EPO), eosinophil cationic protein (E CP), eosinophil-derived neurotoxin (EDN), and the Charcot-Leyden cryst al (CLC) protein (eosinophil lysophospholipase). The production of the mature proteins was demonstrated by Western blotting, and ultrastruct ural analysis demonstrated the presence of immature secondary granules in cells that had been induced to differentiate to eosinophils. These findings demonstrate the utility of the AML14 cell line as a model fo r the study of cytokine induction of eosinophil growth and differentia tion.