Properties of the inferferon-like virus inhibitor released during interaction of mouse sensitized lymphocytes with their target cells

Immune interferon produced in vitro as a quantitative indicator of cell-mediated immunity

The present study was constructed to provide some information on the possibility of utilizing immune interferon as a quantitative indicator of cell-mediated immunity and to clarify some of the nature of immune interferon-producing cells (IIPC). When spleen cells derived from L cell-sensitized mice were co-cultivated with L cells, interferon appeared in the culture fluid. It was shown by additional experiments that the cells responsible for immune interferon production in this system were T-lymphocytes assisted by macrophages. The pattern of kinetics of immune interferon production in vitro was similar to that of migration inhibitory factor or T cell-mediated cytotoxicity.

Effect of serum on the antiviral and anticellular activities of mouse interferon

Fetal bovine serum markedly decreased the ability of mouse L-929 interferon preparations to inhibit the formation of L-929 clones, but did not affect their ability to inhibit vesicular stomatitis virus (VSV) plaque formation in these cells. This dissociation of effects by interferon preparations indicates that: 1. the mechanism of action of interferon for its anticlonal antiviral activities is different; or 2. the molecule responsible for the anticlonal activity is a separate growth inhibitory factor.

Inhibition of macrophage migration by virus-induced interferon preparations

It was found that a preparation of mouse L cell interferon induced by Newcastle disease virus (NDV) possessed not only interferon activity but also inhibitory activity upon migration of guinea pig peritoneal macrophages (MIF activity). These activities were also observed in a preparation of human leukocyte interferon induced by NDV. The interferon and MIF activities shared common characteristics in the dose response, time course of in vitro production, thermal stability, sensitivity to trypsin and periodate, and elution pattern in CM-Sephadex column chromatography. However, gel filtration pattern with Sephadex G-100 showed two separate peaks. Fractions collected from the first peak, corresponding to a molecular weight of about 45 000, had only the MIF activity, while those collected from the second peak, corresponding to a molecular weight of about 30 000, had both the interferon and MIF activities. A preparation of mouse brain interferon induced by Japanese encephalitis virus had a much weaker MIF activity than the L cell interferon, although these preparations were equal in interferon activity (5000 units/ml).