Antitumor effect of natural human tumor necrosis factor-beta against Lewis lung carcinoma in mice and its synergistic potentiation by interferon.

We investigated the antitumor effect of purified natural human tumor necrosis factor-beta (nHuTNF-beta) produced by human acute lymphoblastic leukemia BALL-1 cells stimulated with HVJ on pulmonary metastatic tumors of Lewis lung carcinoma (3LL) transplanted into BDF1 mice. nHuTNF-beta showed antiproliferative effects on metastatic tumors in a dose-dependent manner when administered daily for 10 days by the intravenous route. Histological examination of the tumors treated with nHuTNF-beta revealed that the tumor size and number of metastases were much reduced. Lytic cellular changes, including cytoplasmic vacuolation, loosening of the intercellular junction and both cytoplasmic and nuclear swelling, were found, but tumor necrosis was not. These findings indicate a therapeutic effect of Grade IIa according to the histological criteria of Shimosato and Ohboshi. In addition, synergistic augmentation of the antiproliferative effects of nHuTNF-beta by natural murine interferon-alpha/beta (nMu-IFN-alpha/beta) or recombinant murine interferon-gamma (rMuIFN-gamma) was recognized by median effect plot analysis. The results suggested that nHuTNF-beta may well deserve clinical trial as a new immunotherapeutical agent for human cancer.