Alterations in membrane fluidity of polymorphonuclear leukocytes from children with trisomy 21

Abstract

We investigated plasma-membrane fluidity and heterogeneity of polymorphonuclear leukocytes (PMNs) obtained from seventeen children with trisomy 21. Membrane fluidity and heterogeneity were studied by measuring steady-state anisotropy and fluorescence lifetime of 1-(4-trimethylammoniumphenyl)-6-phenyl-1,3,5-hexatriene (TMA-DPH) incorporated into plasma membranes. The fluorescence anisotropy values in unstimulated PMNs from children with trisomy 21 were significantly higher than those of the control group. The addition of the respiratory burst stimulus phorbol myristate acetate induced a stable and significant increase in fluorescence anisotropy in both groups. These results demonstrate a decrease in membrane fluidity. Moreover, distribution analysis of TMA-DPH lifetime values indicate a decrease in membrane heterogeneity in subjects with trisomy 21. These data suggest changes in the physicochemical properties of the PMN's plasma membrane at the lipid-water interface in children with trisomy 21.