An evaluation of the effects of cytokines on intracellular oxidative production in normal neutrophils by flow cytometry.

To evaluate the effects of inflammatory cytokines on oxidative production in normal neutrophils, seven kinds of cytokines such as granulocyte-macrophage colony-stimulating factor (GM-CSF), granulocyte colony-stimulating factor (G-CSF), interleukin-2 (IL-2), IL-6, IL-1 alpha, IL-1 beta, and interferon-beta (IFN-beta) were tested. The intracellular hydrogen peroxide (H2O2) in individual cells was determined by flow cytometry. According to the levels of intracellular H2O2 enhanced by cytokines, these seven cytokines were classified into three types: (1) prominently effective--GM-CSF; (2) moderately effective--G-CSF, IL-6, and IL-2; (3) weakly or ineffective--IFN-beta, IL-1 alpha, and IL-1 beta. Changes in cell size and cell surface structure after stimulation of those seven cytokines were simultaneously measured by flow cytometry. The most prominently effective cytokine, GM-CSF, initially caused enlargement of cell size and irregularity of the cell surface and subsequently increased H2O2 production by neutrophils. In contrast, the weakly or ineffective cytokines, like IL-1 beta, had no effects on cell size or cell surface. Our study indicates that some kinds of cytokines enhance oxidative production and cause morphological changes in neutrophils.