Macrophage activation by synthetic peptides. II. The effect of oxidative burst products on the fluorescence kinetics of macrophages stained with fluorescein diacetate

Our previous study has shown that the intensity of macrophages in a medium containing fluorescein diacetate (FDA) retains a certain constant level ready to fall upon the addition of stimulants. The decrease in fluorescence was attempted to explain by secretion of oxygen metabolites during the activation process. The decrease in fluorescence is much smaller in the medium containing catalase and superoxide dismutase. Hydrogen peroxide (50 nM and higher) causes a reversible decrease in the fluorescent intensity of resting macrophages. These experiments suggest that the oxidative burst products may serve as regulators of the feedback control during macrophage activation.