Plasma membrane polarity of polymorphonuclear leucocytes from children with primary ciliary dyskinesia

BACKGROUND: Polymorphonuclear leucocytes (PMN) from subjects with primary ciliary dyskinesia (PCD) can have abnormal locomotory systems. The locomotory activity of PMN is the result of biochemical events mediated by the plasma membrane. In this study we investigated plasma membrane polarity of PMN from children with PCD. DESIGN: Membrane polarity was studied in 11 children with PCD and in healthy controls by measuring the steady-state fluorescence excitation and 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 red shift in polar solvents, with respect to nonpolar solvents. Moreover, the effect of the microtubule disassembling agent colchicine on PMN membrane polarity was evaluated. RESULT: Our results show a red shift of the fluorescence excitation and emission spectra of Laurdan in PMN from the PCD group with respect to the control group. These data indicate an increase in membrane polarity of PMN from the PCD group. Treatment of PMN with colchicine induced a red shift in the Laurdan excitation and emission spectra with the same trend observed in PMN from the PCD group. CONCLUSION: PMN from children with PCD are characterized by an increased plasma membrane polarity. These changes could be the basis of the modifications in the locomotory activities of PMN. The observed alterations may be attributed to abnormalities in the cytoskeleton.