The effect of Cytokines on the Differentiation of an Eosinophilic Leukemia Cell Line (EoL-1) is Associated with Down Regulation of c-myc Gene Expression

In this study, we measured hydrogen peroxide (H₂O₂) release as one of the functions of mature eosinophils, and utilized it as a quantitative index. Wedemonstrated that 1) the human eosinophilic leukemia cell line, EoL-1, did not release H₂O₂ when stimulated with phorbol myristate acetate (PMA), but after culturing with tumor necrosis factor (TNF) and interferon-γ (IFN-γ) it acquired the ability to release H₂O₂; 2) the ability to release H₂O₂ was time dependent and reached a peak after 4 days of culture; 3) administration of TGF-β or GM-CSF, with TNF and IFN-γ enhanced the PMA-induced release of H₂O₂ from EoL-1. To examine the potential relationship between c-myc gene expression and induction of the ability to release H₂O₂, Northern analysis of c-myc gene expression in EoL-1 cocultured with TNF and IFN-γ was performed. The results showed that the c-myc gene was spontaneously expressed in EoL-1, and the level of c-myc mRNA was markedly reduced after the cells were cocultured with TNFand IFN-γ, suggesting that the decrease of the c-myc mRNA level is closely associated with induction of the ability to release.