In vitro antiviral properties of endotoxin-activated rat Kupffer cells.

Kupffer cells isolated from the liver of normal rats were checked for their antiviral activities. The intrinsic antiviral effect against vaccinia virus was high whether the cells were activated in vitro with endotoxin or not. The expression of the extrinsic antiviral activity measured by mixing isolated Kupffer cells with vaccinia-virus-infected target cells was remarkably enhanced by prior treatment of the Kupffer cells with LPS. Interferon was shown to be not responsible for that inhibitory activity. Different experimental data suggest that the virus replication in the target cells is blocked at a late stage in the replication cycle.