Combination of interleukin-2 and irradiation in therapy of murine tumors

Interleukin-2 therapy of lymphoma-bearing immunosuppressed mice

In the present study, the immune status of syngeneic Balb/c animals bearing a poorly metastatic RAW117-P lymphoma and the highly malignant liver metastatic variant RAW117-H10 lymphoma were measured and compared to control animals with no known tumor. The immune status was evaluated by performing various analyses of spleen cells for the frequencies of immune cells using flow cytometry, in vitro mitogen response and in vitro NK cell-mediated cytotoxicity assays on days 6, 9 and 12 after tumor transplantation. The results of these studies indicated that from day 9 onwards, some of the immune response of the RAW117 lymphoma-bearing animals appeared to decrease compared to control animals. In order to boost the immune response of the tumor-bearing immunosuppressed animals, recombinant interleukin-2 (rIL-2) was administered to RAW117-H10 lymphoma-bearing animals. The immune status of tumor-bearing animals treated with rIL-2 was evaluated on days 5, 10 and 15 after tumor transplantation using similar analyses of spleen cells as described above. The results of these experiments indicated that IL-2 treatment increased splenic levels of cytotoxic cells, and decreased the in vivo tumorigenicity/metastasis of metastatic RAW117-H10 lymphoma cells. rIL-2 administration resulted in a significant increase in survival of tumor-bearing animals, and histological studies showed significantly lower tumor burdens in treated animals: it appears that rIL-2 has a beneficial therapeutic effect on immunosuppressive metastatic RAW117 lymphoma.