Oligo‐2′,5′‐Adenylate Synthetase Activity in Cells Persistently Infected with Human T‐Lymphotropic Virus Type I (HTLV‐I)

Spontaneous production of interferon‐gamma (IFN‐γ) was shown in several T‐lymphoblastoid cell lines persistently infected with human T‐lymphotropic virus (HTLV‐1). However, the produced IFN‐γ was not always associated with the induction of the antivirus state. The induction of oligo‐2′,5′‐adenylate synthetase (2‐5AS) by IFN was studied in five human T‐cell lines persistently infected with HTLV‐I (MT‐1, MT‐2, SMT‐1, HUT 102 and OKM‐2). Four cell lines are able to produce IFN‐γ spontaneously, while the OKM‐2 cell line is not. Poor induction of 2‐5AS was recognized in three (MT‐1, MT‐2 and SMT‐1) of the four cell lines producing IFN‐γ, though the poor induction was improved after long‐term cultivation of cells with IFN‐α. On the contrary, in the OKM‐2 cell line. significant activity of the enzyme was induced by IFN‐α. Induction of 2‐5AS was not correlated with cell growth inhibition, but with the antivirus state. Furthermore, an inverse relationship between IFN‐γ production and 2‐5AS induction was demonstrated in these cell lines with the exception of HUT 102 cells.