Induction of differentiation into monocyte/macrophage cell lineage of a human eosinophilic leukaemia cell line EoL-1 by simultaneous stimulation with tumour necrosis factor-alpha and interferon-gamma.

Human myeloid leukaemia cell lines have been shown to differentiate into distinct cell lineages in vitro in response to several differentiation-inducing agents. A human eosinophilic leukaemia cell line, EoL-1, has been shown to differentiate into mature eosinophilic granulocytes by treatment with the culture supernatant of a human T-cell line, HIL-3. In this study we have studied whether the EoL-1 cell line has potential to differentiate into cell lineage other than eosinophils. We found that EoL-1 cells cultured in the presence of tumour necrosis factor (TNF)-alpha (10 u/ml) and interferon (IFN)-gamma (1000 u/ml) for 2-4 d differentiated into macrophage-like cells in morphology, and expressed CD14 antigen on their cell surface. It is possible that the small subpopulation of EoL-1 cells which contains non-specific esterase (NSE) activity may be preferentially differentiated by TNF-alpha and IFN-gamma. To clarify this issue, we have cloned the EoL-1 cell line and obtained NSE negative and positive sublines. Both EoL-1 sublines differentiated into monocyte/macrophage-like cells, because: (a) EoL-1 sublines were induced to express CD14 antigen, and (b) they attached firmly to the plastic wells; (c) after differentiation they became strongly positive for NSE staining, and secreted TNF-alpha in response to the stimulation with lipopolysaccharide; and (d) they exhibited potent phagocytic activity. Therefore, we found that the EoL-1 cell line has the ability to differentiate not only into mature eosinophilic cells but also into monocyte/macrophage cell lineage, suggesting that EoL-1 cells represent immature cells with ability to differentiate into multiple cell lineages.