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-gamma) was shown in several T-lymphoblastoid cell lines persistently infected with human T-lymphotropic virus (HTLV-1). However, the produced IFN-gamma 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-gamma 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-gamma, though the poor induction was improved after long-term cultivation of cells with IFN-alpha. On the contrary, in the OKM-2 cell line, significant activity of the enzyme was induced by IFN-alpha. Induction of 2-5AS was not correlated with cell growth inhibition, but with the antivirus state. Furthermore, an inverse relationship between IFN-gamma production and 2-5AS induction was demonstrated in these cell lines with the exception of HUT 102 cells.