[Use of fluorescein diacetate for research on macrophage activation]

Kinetic of changes in the fluorescence intensity of macrophages in a medium containing fluorescein diacetate (FDA) has been analysed. It is shown that under certain conditions the intensity of macrophages retains a constant level for rather a long time. The addition of stimulants such as lipopolysaccharide or tuftsin to the incubation medium leads to characteristic changes in the cell fluorescence level related to the increase in the activity of FDA intracellular hydrolyses and fluorescein efflux from macrophages. It is concluded that the kinetic of changes in the macrophages fluorescence intensity in a medium with FDA may serves as a test for detecting early functional changes upon macrophage activation.