The beta-gal interferon assay: a new, precise and sensitive method

J Interferon Cytokine Res. 1998 Jul;18(7):451-60. doi: 10.1089/jir.1998.18.451.

Abstract

Cells of a human glioblastoma line were stably transfected with a glial fibrillary acidic protein (GFAP) promoter sequence/lacZ reporter gene. Following this modification, they produced Escherichia coli beta-galactosidase constitutively in amounts that could be measured through their conversion of an added fluorophore into a product readily estimated by fluorimetry. Human interferons (IFN) selectively and in a dose-dependent manner reduce the formation of beta-galactosidase in this system. We have used it as the basis for a novel assay that is sensitive (4-40 pg/ml), precise, completed in 30 h, and applicable to both type I and type II human IFNs. Statistical analysis showed interassay relative standard deviations ranging from 5% to 11%, and most individual assays revealed potencies with limits of error within 85%-115%. Neither partially trypsin-digested IFN nor the other cytokines and mitogens we tested reacted in this system, except for tumor necrosis factor-alpha (TNF-alpha). The high selectivity was further shown by the loss of response to IFN in the presence of the appropriate specific anti-IFN or anti-IFN-gamma receptor antibodies.

MeSH terms

  • Biological Assay
  • Fluorometry
  • Genes, Reporter
  • Humans
  • Interferons / pharmacology*
  • Plasmids / genetics
  • Reproducibility of Results
  • Sensitivity and Specificity
  • Tumor Cells, Cultured
  • beta-Galactosidase / biosynthesis*

Substances

  • Interferons
  • beta-Galactosidase