Differentiation of PLB-985 myeloid cells into mature neutrophils, shown by degranulation of terminally differentiated compartments in response to N-formyl peptide and priming of superoxide anion production by granulocyte-macrophage colony-stimulating factor.

Mature blood neutrophils have a short lifespan in vitro and are not easily transfectable. We obtained terminally mature neutrophils after differentiation of immature transfectable PLB-985 myeloid cells by treatment with dimethylformamide (0.5%), Nutridoma SP (1%) and fetal calf serum (0.5%). Maturation was shown by functional degranulation, in response to bacterial N-formyl peptide (fMLP), of specific granules and secretory vesicle contents; the latter emerge during the last step of normal neutrophil differentiation into bone marrow. These differentiated cells also produced quantities of superoxide anion similar to those produced by blood neutrophils, in response to physiological stimuli (fMLP); in addition, the fMLP-induced respiratory burst was primed by the proinflammatory cytokine granulocyte-macrophage colony-stimulating factor. Thus, in our experimental conditions, PLB-985 cells transformed into fully differentiated neutrophils capable of fine regulation by inflammatory agents. This cell model will help in the understanding of the molecular mechanisms underlying neutrophil functions.