Comparative study on the anticellular and antiviral effects of interferon and the haemopoietic stem cell inhibition factor.

Pretreatment with crude interferon preparations obtained from suspension cultures of bone marrow, spleen and thymus cells or from mouse L-cell cultures or with mouse serum interferon preparations did not change the colony-forming activity of bone marrow cells on syngeneic transplantation to lethally irradiated mice. Preparations of L-cell culture interferon, dialysed and purified by carboxymethyl-Sephadex (G-25) column chromatography, showed an inhibitory effect on exogenous colony formation by bone marrow cells. The results suggested the presence in crude interferon preparations of a substance either inhibiting the anticellular effect of interferon or stimulating colony formation. The factor produced by thymus cells following their treatment with antilymphocyte serum inhibited colony formation by bone marrow cells and, unlike interferon, possessed no antiviral activity when tested in cell cultures.