Plasma Membrane Biophysical Properties Linked to the Antiproliferative Effect of Interferon-α

Balint, Elisabeth and Grimley, Ph. M. and Gan, Yuxiang and Zoon, Kathryn C. and Aszalos, A. (2005) Plasma Membrane Biophysical Properties Linked to the Antiproliferative Effect of Interferon-α. Acta Microbiologica et Immunologica Hungarica, 52 (3-4). pp. 407-432. ISSN 1217-8950

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Abstract

The relationship of plasma membrane biophysical properties to the antiproliferative effect of interferon-alpha (IFN-a) was investigated in Daudi lymphoblasts cell lines with sensitivity to growth inhibition, parallel clonal variants selected for resistance, and one revertant subclone. Lateral mobility of surface differentiation antigens (I2, CD19, CD20, and sIgM-k) were measured by fluorescence recovery after photobleaching (FRAP). The mean diffusion coefficients, D, values for two clones of IFN-a resistant Daudi cells were significantly higher (D = 8.1-11 × 10-10 cm2/sec) than for parental sensitive cells (D = 4.9-7.4 × 10-10 cm2/sec). Microviscosity of the plasma membranes were probed by electron spin resonance (ESR) spectrometry. These results also indicate a greater degree of molecular motional freedom in resistant cells. Treatment of sensitive lymphoblasts with IFN-a (100-400 U/106 cells) for 5-30 min consistently increased mean values of D and the degree of spin-probe motional freedom, whereas no significant differences were detected in resistant cells. The effect of IFN-a on the membrane potential (Em) of Daudi cells was quantitated by flow cytometry using a voltage-sensitive oxonol dye. Membrane potential of all clones was similar (-50 to -56 mV). Treatment with IFN-a for 8-10 min caused hyperpolarization in the sensitive cells (DEm up to 45 mV), but only minimal hyperpolarization in the resistant ones (DEm up to 7 mV). We concluded that sensitivity to IFN-a and treatment with IFN-a are related to the biophysical status of plasma membranes.

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