In Vivo Administration of Tumor Necrosis Factor- α is Associated with Antiviral Activity in Human Peripheral Mononuclear Cells

Abstract

Tumor necrosis factor-α (TNF-α) has a spectrum of biologic effects and has been shown to exert antiviral effects in fibroblasts in vitro. The in vivo administration of TNF-α (40–160 μg/m² intravenously over 2 hr) and its effects on vesicular stomatitis virus (VSV) replication in peripheral blood mononuclear cells (PBMC) from patients with malignancy was investigated. Blood was obtained before, during, and after infusion. The PBMC were separated and infected with VSV at a multiplicity of infection of 0.005 plaque-forming units/cell and virus yields were determined 72 h later. The TNF-α inhibited VSV yields by as much as 99% in a dose-dependent manner with the inhibition initially observed during the first hour of infusion. Despite a rapid reduction in TNF-α serum levels, the higher doses still produced antiviral effects 4 hr after the infusion. Sera obtained at identical times had no interferon activity. Human γ-interferon (25 μg/ml) added in vitro augmented the TNF-α-induced inhibitory activity in both magnitude and duration. Percentages of lymphocytes and monocytes in peripheral blood were reduced at 4 hr after TNF-α administration and the monocyte to lymphocyte ratio was diminished and temporally coincided with the loss of TNF-induced antiviral state. These data suggest that the in vivo administration of TNF has a direct inhibitory activity on VSV replication in human peripheral blood mononuclear cells that was enhanceable by γ-interferon and possibly monocyte mediated.