Inhibition of Haemopoietic Colony Growth by Interferon Preparations from Different Sources

Abstract

INTERFERON preparations have been shown to inhibit the multiplication of tumour cells in vitro^1–4 and more recently comparable preparations have also been shown to inhibit normal cell division. Thus, inhibition has been observed in %of mouse embryo fibroblasts⁵, of weanling mouse kidney⁵, of stimulated mouse lymphocytes⁶ and of the formation of granulocyte/macrophage colonies derived from mouse and rabbit bone marrow^7–9. In the course of investigating the effect of mouse and rabbit interferons from different sources on bone marrow colony formation in agar, it became apparent that a strict correlation did not always exist between the antiviral titre and the colony inhibiting titre of interferon preparations derived from cell culture interferon, whereas it did exist when interferon preparations derived from mouse serum or brain were used. The development of granulocyte/macrophage colonies in agar is dependent upon the presence and concentration of colony stimulating factor (CSF)¹⁰, so the most likely explanation for the lack of correlation observed in testing some interferon preparations was the presence of significant amounts of CSF in these preparations. The results of the experiments presented here support this hypothesis and suggest the possibility that both CSF and interferon may be mutually antagonistic regulators of cell division.