Immunoregulation during acute infection with Epstein-Barr virus: dynamics of interferon and 2',5'-oligoadenylate synthetase activity.

Immunoregulation during acute infection with Epstein-Barr virus (EBV) is incompletely understood, although species of interferon (IFN) may be important immunoregulatory molecules. IFN, 2',5'-oligoadenylate (2',5'-A) synthetase (an IFN-induced enzyme), T and natural killer cell subsets, and natural and anomalous killer cell functions were studied systemically during acute infectious mononucleosis. Serum IFN was not detected (less than 1 international unit/ml) during infection. 2',5'-A synthetase activity was significantly increased in the acute phase of infection when compared with convalescence (34.5 +/- 6.5 vs. 3.6 +/- 1.2 nmol ATP/mg of protein per hr; P less than .01 by Student's t test). A generalized IFN effect was suggested by elevated 2',5'-A synthetase activity in purified neutrophil preparations. Sequential studies revealed a correlation between peak elevations of 2',5'-A synthetase activity and increased percentages of cytotoxic/suppressor cells as well as anomalous killer cell activity against an EBV-infected B cell line. Thus IFN may act as an immunoregulatory lymphokine early in the course of acute EBV infection.