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

Area of Science:

• Biochemistry
• Molecular Biology
• Cell Biology

Background:

• Glioblastoma cells can be genetically modified to express reporter genes.
• Glial fibrillary acidic protein (GFAP) promoter activity can be regulated by cellular factors.
• Human interferons (IFN) are crucial signaling proteins with diverse biological effects.

Purpose of the Study:

• To develop a novel, sensitive, and precise assay for quantifying human interferon (IFN) activity.
• To utilize a genetically engineered glioblastoma cell line expressing a lacZ reporter gene for IFN detection.
• To establish an assay applicable to both type I and type II human IFNs.

Main Methods:

• Stable transfection of glioblastoma cells with a GFAP promoter/lacZ reporter gene construct.
• Constitutive expression of Escherichia coli beta-galactosidase, measured via fluorimetry.
• Quantification of IFN-induced reduction in beta-galactosidase activity.
• Testing selectivity against other cytokines and mitogens, including TNF-alpha.

Main Results:

• The assay demonstrated high sensitivity (4-40 pg/ml) and precision (interassay RSD 5%-11%).
• The assay accurately measured potency with limits of error within 85%-115%.
• The system showed high selectivity for IFNs, with minimal cross-reactivity, except for TNF-alpha, and response was blocked by specific antibodies.

Conclusions:

• A novel, sensitive, and precise assay for human IFN activity has been established using a GFAP-promoter driven lacZ reporter system.
• The assay is rapid (30 h) and applicable to both type I and type II human IFNs.
• The high selectivity and precision make this assay valuable for interferon research and diagnostics.