[The state of hyporeactivity in interferon production: localization and partial purification of the factor repressing...

The hyporeactivity factor in interferon production by L-929 cells designated IRP (interferon repressing protein) has been studied. In particular, its localization and methods of its purification have been studied. The kinetics of IRP accumulation by producing cells correlate with the development of hyporeactivity condition. Most of IRP is localized in cell sap and in ribosomal fraction in evidence to regulatory role of repressor at the level of interferon mRNA translation. A 100-fold increase in repressor activity was achieved by IRP concentration by ammonium sulfate precipitation. IRP as well as interferon have been shown to possess high affinity to polyU sepharose. The preparations of IRP and interferon concentrated by ammonium sulfate precipitation were subsequently purified by fractioning in a polyI sepharose column. A 10,000-fold (6 x 10(4) U/mg) purification was achieved for IRP and 250-fold (10(4) U/mg) for interferon.