The effect of a lymphotoxin-like substance, OH-1, released by human acute lymphatic leukemia BALL-1 cells, on metastatic tumor proliferation was investigated in BDF1 mice with transplanted Lewis lung carcinoma cells. Mitomycin-C, cyclophosphamide and adriamycin were used as control agents. The effect of OH-1 on metastases, as determined by comparison of the numbers of pulmonary nodules and by 3H-thymidine labeling indices, was significant. Also, investigation of the effect of OH-1 on host immunity showed that, while the control preparations had considerable side effects, immunodepression and emaciation were not noted with OH-1. As to direct cytotoxicity, OH-1 is principally cytostatic in activity and effects cell progression delay in both the G1 and G2 phases.</p
