Use of Laurdan fluorescence in studying plasma membrane organization of polymorphonuclear leukocytes during the respiratory burst.

The changes in plasma membrane polarity of polymorphonuclear leukocytes (PMN) during the activation of the respiratory burst were investigated by measuring the steady-state fluorescence emission spectra of 2-dimethylamino(6-lauroyl) naphthalene (Laurdan), which is known to be incorporated at the hydrophobic-hydrophilic interface of the bilayer, displaying spectral sensitivity to the polarity of its surroundings. Laurdan shows a marked steady-state emission blue shift in nonpolar solvents, with respect to polar solvents. Our results show a blue shift of the fluorescence emission spectra of Laurdan during activation of PMN with phorbol myristate acetate or N-formyl-methionyl-leucyl-phenylalanine. These results suggest that the activation of the respiratory burst of PMN is accompanied by a decrease in polarity in the hydrophobic-hydrophilic interface of the plasma membrane.