Flow cytometric analysis of cell membrane events induced by interferon-alpha

Laser-based flow cytometer permits prompt experimental monitoring of fluctuations in the molecular status of cell surface membranes and can report the occurrence of early signal transduction events of interferons. The interferons are important regulatory molecules, capable of affecting a number of cell functions in addition to the much studied proliferation of the variety of cell types, inhibition of viral replication and growth. Clinically there is increasing importance of anticancer and antiviral activity of interferon-alpha (IFN). IFN acts primarily by interaction with membrane receptors during signal transduction. The aim of this study was to pursue the importance of the cell membrane changes in the signal transduction of IFN from receptor binding to biological effect. Studies were therefore undertaken to measure the absolute membrane potential of IFN treated cells. The absolute membrane potential of human cells was quantitated by flow cytometry using a voltage-sensitive oxonol dye. The relationship of plasma membrane biophysical properties to the expression of IFN effects was investigated on different types of model cells (U937 monocytes and Daudi lymphoblast). Our studies have suggested changes in the plasma membrane environment after IFN treatment, including changes in the ion flux, membrane potential, alteration of microviscosity, etc.