MIF-like activity in non-stimulated and virus infected cell cultures.

Macrophage-migration inhibition factor (MIF) is a lymphocyte-derived substance which plays an important role in cell mediated immunity. Soluble factors containing MIF-like activity and produced by non-stimulated and virus-infected non-lymphoid cell cultures have also been reported. In the present study, a MIF-like factor was repeatedly detected in Buffalo green monkey kidney cells infected with mumps and herpes simplex virus type 1 (HSV-1) indicating that this substance is reproducible and can be stimulated by two viruses of widely varying groups. Wistar-38 (WI-38) cell cultures also increased production of this substance in response to mumps but not HSV-1 infection, indicating that the production of this factor is not necessarily induced by all viruses. A factor which stimulated the spread of macrophages was also found to be induced in WI-38 cells by both viruses, suggesting yet another substance produced by non-lymphoid cells in response to viral infection. The ability of non-stimulated WI-38 cells to produce MIF-like activity was also confirmed, and this factor could be further stimulated or opposed by viral infection.