Abstract
We have developed a bioassay for interferons (IFN) based on measuring the amounts of 2′,5′ oligoadenylate synthetase (2-5AS) induced in cells of the THP-1 monocyte line in response to IFN. The assay can be completed in 20 h, gives reproducible results, and is at least 50 times more sensitive to IFN-α than conventional cytopathic effect inhibition antiviral assays. It is, respectively, less and much less sensitive to IFN-β and IFN-γ. The presence of preexisting 2-5AS activity in a sample does not influence the results. We have used this assay to measure very low levels (0.1–0.5 IU/ml) of endogenously formed IFN-α in serum samples from patients with various diseases and also to measure the residual small amounts of IFN-α still present in the serum as late as 48 h after an i.m. injection of 3 million IU, which is appreciably later than in previous methods. Thus, our highly sensitive assay offers considerable advantages, not least in relation to the clinical use of IFN.
Get full access to this article
View all access options for this article.