Synergistic anti‐tumor effects of combined IL‐1/IFN‐α/β therapy in mice injected with met astatic friend erythroleukemia cells

Peritumoral injection of relatively low doses of either mouse interferon (IFN)‐α/β (10,000‐20,000 unit/injection) or of recombinant human interleukin‐I (IL‐1) β (125‐250 ng/ injection) in mice transplanted S.C. with Friend erythroleukemia cells (FLC) resulted in some inhibition of primary tumor growth, inhibition of liver and splenic metastases and increased survival time. A synergistic anti‐tumor effect was observed in mice injected with both IL‐l and IFN‐α/β. Highly purified mouse IFN‐β also exerted a synergistic anti‐tumor effect when combined with IL‐I‐β in mice injected with FLC. The anti‐tumor action of IL‐I/IFN was markedly reduced in mice treated with antibodies to CD4 antigens. Antibodies to asialo‐GM 1 also diminished the anti‐tumor effect by the combined cytokine treatment. The combined IL‐I/IFN therapy was effective in NK‐deficient bg/bg mice, although the extent of the anti‐tumor response in these mice was less than that observed in bg/+ mice.