Gilles Merlin

ASSAY OF AN INTERFERON-INDUCED ENZYME IN WHITE BLOOD CELLS AS A DIAGNOSTIC AID IN VIRAL DISEASES

Interferon is part of the system of defence against viral infections and has important cell-regulatory and immunoregulatory functions. It is, however, not always possible to quantify circulating interferon in patients. An assay has been developed to measure an interferon-induced enzyme in white blood cells. The activity of this enzyme is constant in healthy subjects but increases by 2-10 times in 85% of patients with acute viral infections. It is also enhanced in autoimmune diseases and in virus-related malignancies and neurological disorders. The enzyme level was not raised in bacterial infections or non-infectious diseases studied. This simple and rapid biochemical assay of the interferon system could be used for diagnosis and evaluation of many diseases.

The interferon-induced enzyme oligo-isoadenylate synthetase: Rapid determination of its in vitro products☆

Abstract A procedure for rapid isolation of the products of the interferon-induced enzyme, oligoisoadenylate synthetase, is described. After incubation of [α- 32 P]ATP with the poly(rI): (rC)-adsorbed fraction of cellular proteins, the products are treated with phosphatase. Aliquots of the nucleotides are then applied on small columns which contain 300 μl of alumina powder and eluted with 3 ml of 1 m glycine-HCl buffer, pH 2.0. The labeled free phosphate, released by the phosphatase treatment, is efficiently adsorbed by the alumina, while the phosphatase-resistant cores of the oligo-isoadenylates, up to the length of pentamer, are eluted. Larger oligomers are only partially recovered. We successfully applied this method for determination of the level of the enzyme in multiple samples of cell homogenates.

INTERFERON-INDUCED PROTEINS: BIOLOGICAL FUNCTIONS AND CLINICAL APPLICATIONS

ABSTRACT The induction by Interferons of the synthesis of specific cellular proteins can be applied to investigate whether cells have been exposed to IFNs. For both the (2′-5′) oligo A synthetase and the HLA cell surface antigens, induction by IFNs was demonstrated at the level of mRNA, and the specificity for various IFNs was studied. Clinical applications of the synthetase assay in peripheral white blood cells are described.