Introduction

Interferons are pleotropic cytokines with antiviral, antiproliferative and immunomodulatory activities. Activity can be assayed by any of these methods; however the standard assay is protection of cells from the cytopathic effect (CPE) of certain viruses. In part, this preference is historical, since this was the initial activity which defined these molecules. The other reason that the CPE assay is used to characterize the activity of interferons (IFN) is that it is amongst the most sensitive activity assay, with often >100 fold more sensitivity than the alternatives. In fact, given that the K_d of IFN on human cells is ~0.5 nM and in some antiviral assays the IFN is effective at 0.5 pM, very little receptor occupancy is required for protection of the test cells from viral challenge..

For research use only, not for diagnostic or therapeutic use.