MEROCYANINE-540 AND 2-PHASE PARTITIONING DETECT INTERFERON-BETA(SER)-INDUCED PLASMA-MEMBRANE ALTERATIONS IN DAUDI LYMPHOMA-CELLS

The amphipathic fluorescent dye, merocyanine 540 (MC540) and partition ing in aqueous two-phase systems were used to analyze interferon-beta( ser) (IFN-beta(ser))-induced plasma membrane changes in Daudi cells. T he distribution of cells in charge-sensitive and lipid-sensitive two-p hase systems indicated that the surfaces of IFN-beta(ser)-treated cell s were more lipophilic and more electronegative than those of their un treated counterparts. Cells that were grown in the presence of IFN-bet a(ser) (100 IU/ml) for 24-48 hours bound more MC540 than control cells but their susceptibility to dye-sensitized photoinactivation remained unchanged. The enhanced expression of dye binding sites in IFN-beta(s er)-treated cells may explain part but not necessarily all of the occa sionally observed transient increases of MC540-reactive cells in perip heral blood.