A comparison of interferon levels with leukocyte (2'-5') oligoadenylate synthetase activity as markers of viral encephalopathies.

The activity of (2'-5') oligoadenylate synthetase in peripheral blood mononuclear leukocytes (PMLs) was compared with serum and cerebrospinal fluid (CSF) levels of interferon in 26 patients with acute encephalopathies including 19 with viral encephalitis. Elevated activity of (2'-5') oligoadenylate synthetase was found in 2 patients with viral encephalitis, one patient with a virus-associated encephalopathy, and one patient with intracerebral hemorrhage. High activity was also found in PMLs from 1 of 16 asymptomatic patients 6-8 months after recovery from their encephalopathies. Significant titers of interferon were detected in 8 patients with viral encephalitis and no patients with other diagnoses. Combined measurement of interferon in CSF and serum appears both more sensitive and more specific than assay of (2'-5') oligoadenylate synthetase in PMLs as a diagnostic aid in viral encephalitis.