In vivo augmentation of the cytotoxicity of spleen lymphocytes against syngeneic B-16 melanoma cells and the suppression of the artificial metastases in C57BL/6 mice by subcutaneous multiple injections of high dose human recombinant interleukin-2 (rIL-2).

The cytotoxicity of spleen lymphocytes against YAC-1 cells, against syngeneic B-16 and F-10 melanoma cells was augmented not only by incubation of spleen lymphocytes with human recombinant interleukin-2 (rIL-2) in vitro, but also by injecting C57BL/6 mice with high dose rIL-2 for more than 3 consecutive days. In animals injected s.c. with multiple high dose rIL-2, the numbers of tumor nodules in the lung were significantly decreased 21 days after i.v. tumor inoculation. In addition, in these groups of animals no liver metastases were observed although liver metastases were detected in 6/11 control mice.