EFFECT OF PAF ON HUMAN LYMPHOCYTE MEMBRANES - A FLUORESCENCE STUDY

We have studied the effect of platelet-activating factor (PAF) on the physico-chemical organization of human lymphocyte plasma membranes by measuring the steady-state fluorescence anisotropy and the fluorescenc e decay of trimethylammoniumphenyl)-6-phenyl-1,3,5-hexatriene (TMA-DPH ) incorporated in lymphocyte plasma membranes. PAF induced a time-limi ted and significant increase of the lipid order in the exterior part o f the membrane and a decrease in membrane heterogeneity. These changes were blocked in the presence of PAF antagonist L-659,989. The results indicate that the observed changes in the physico-chemical properties of the lymphocyte plasma membranes may be attributed to a PAF-recepto r interaction.