EFFECT OF CETIRIZINE ON PLASMA-MEMBRANE OF HUMAN EOSINOPHILS, NEUTROPHILS AND PLATELETS - A DOSE-RESPONSE STUDY

The effect of different concentrations of cetirizine (0.1, 0.3, 0.5, 0 .7, 0.9 ug/ml) on plasma membrane fluidity and heterogeneity of human eosinophils, neutrophils and platelets were investigated using a fluor escence technique. Membrane fluidity and heterogeneity were studied by measuring the steady-state fluorescence anisotropy and fluorescence d ecay of trimethylammonium-phenyl)-6-phenyl-,3,5-hexatriene (TMA-DPH) i ncorporated in the membrane. Our results demonstrate that cetirizine i nduced a significant increase in the lipid order in the exterior part of the membrane and a decrease in membrane heterogeneity of eosinophil s at concentrations of 0.7 ug/ml and higher and that at a concentratio n of 0.9 ug/ml it does likewise in neutrophils and platelets. Moreover , cetirizine abolished the PAF induced changes in membrane fluidity in these cells. These data suggest that cetirizine interacts with the pl asma membrane of eosinophils, neutrophils and platelets inducing funct ional changes.