A STUDY OF THE INTERACTION BETWEEN CETIRIZINE AND PLASMA-MEMBRANE OF EOSINOPHILS, NEUTROPHILS, PLATELETS AND LYMPHOCYTES USING A FLUORESCENCE TECHNIQUE

THE effect of cetirizine on plasma membrane fluidity and heterogeneity of human eosinophils, neutrophils, platelets and lymphocytes was inve stigated using a fluorescence technique. Membrane fluidity and heterog eneity were studied by measuring the steady-state fluorescence anisotr opy and fluorescence decay of 1-(4-trimethylammonium-phenyl)-6-phenyl- 1, 3, 5-hexatriene (TMA-DPH) incorporated in the membrane. The results demonstrate that cetirizine (1 mug/ml) induced a significant increase in the lipid order in the exterior part of the membrane and a decreas e in membrane heterogeneity in eosinophils, neutrophils and platelets. Moreover, cetirizine blocked the PAF induced changes in membrane flui dity in these cells. Cetirizine did not influence significantly the pl asma membrane of lymphocytes. These data may partially explain the eff ect of cetirizine on inflammatory cell activities.