Anti‐tumor effects of interferon in mice injected with interferon‐sensitive and interferon‐resistant friend leukemia cells. V. Comparisons with the action of tumor necrosis factor

Abstract

A number of similarities and dissimilarities in the anti‐tumor effects of TNF and interferon α/β have been observed in DBA/2 mice injected with Friend erythroleukemia cells (FLC). Mouse TNF exerted marked anti‐tumor effects in mice injected either s.c. or i.p. with FLC lines 3C 18 or 3 γR8 resistant in vitro to the cytotoxic effects of TNF. Likewise, mouse interferon α/β had anti‐tumor activity in mice injected with these FLC, resistant to the action of interferon α/β or γ in vitro. The results of histopathologic examination and ³¹P nuclear magnetic resonance analyses of 3C18 FLC s.c. tumors injected with TNF resembled the results previously obtained for 3C18 FLC tumors injected with interferon α/β, although the effects of TNF occurred more rapidly. Injection of mice with antibody to mouse interferon α/β or γ did not abrogate the anti‐tumor effects of TNF in mice injected i.p. with FLC. Our results suggest that in this experimental system the anti‐tumor effects of TNF, like interferon α/β, do not result from a direct effect on the tumor cells themselves but are host‐mediated.