Epstein-Barr virus-infected B lymphoblastoid cell lines: dynamics of interferon and 2'5'-oligoadenylate synthetase activity.

Levels of 2'-5'-oligoadenylate synthetase (2'-5'OAS) activity measured in cell-free extracts of 23 Epstein-Barr virus transformed beta lymphoblastoid cell lines (LCL) were measured. Enzyme activity was low during stationary or log phase growth, and rapidly rose to peak values during log phase. Peak levels of 2'-5'OAS activity were characteristic for each LCL, and were significantly higher (P less than 0.05) in lines derived from patients with infectious mononucleosis (IM) than in lines from healthy individuals. Peak 2'-5'OAS activity correlated with maximal titers of endogenous human interferon-alpha (HuIFN-alpha); (r = 0.80). Enzyme activity levels could be increased by treating LCLs with exogenous HuIFN-alpha, or decreased by neutralization of endogenous interferon with antibody to HuIFN-alpha. 2'-5'OAS activity always peaked during log-phase growth, even in cultures depleted of interferon by antibody and in cultures which did not produce interferon. Thus, although peak levels of 2'-5'OAS activity in a given LCL correlated with maximal interferon titers, the growth phase associated variations in enzyme activity were independent of interferon. We conclude that regulation of constitutive levels of 2'-5'OAS in LCLs is partially independent of interferon.