Enhanced activity against syngeneic murine tumors by intrasplenic injection of recombinant interleukin-2 (IL-2) and interleukin-1 (IL-1).

The antitumor activity of Interleukin-1 (IL-1), was assessed against the murine adenocarcinoma colon 26 tumor model in combination with Interleukin-2 (IL-2). Colon 26 tumor cells were inoculated on the back of syngeneic BALB/c mice. Fourteen days after inoculation, when the tumor nodule reached approximately 10 mm in diameter, tumor nodules were resected and Hank's solution, IL-2, IL-1, or IL-2 plus IL-1 were injected directly into the mouse spleen. One week after treatment, potent natural killer (NK) and enhanced lymphokine activated killer (LAK) cell activities were seen in the splenocytes treated by the combination of IL-2 plus IL-1. Furthermore the combination treatment by IL-2 plus IL-1 resulted in a significantly prolonged survival. Phenotypic analysis showed an increased number of percent positive cells expressing asialo GM 1 and IL-2 receptor after treatment with IL-2 plus IL-1. A possible role of IL-1 in augmentation of IL-2 dependent antitumor activity in vivo is discussed.