Induction of lymphokine activated killer (LAK) and prolongation of its activity by intrasplenic injection of interleukin 2 (IL-2) in combination with tumor necrosis factor (TNF)

We have so far investigated the method to induce LAK cells efficiently within the body by direct intrasplenic injection of Interleukin 2 (IL-2) in tumor bearing mice. In this study we used IL-2 in combination with rTNF in an attempt to induce effectively much stronger LAK cells and found that the combined use resulted in not only enhancement but also significant prolongation of LAK activity. Furthermore, the combined use also yielded in vivo effect, that is prolongation of the mouse survival. This study suggests that the combined use of IL-2 and TNF may promise more effective induction of LAK cells in the organism with much smaller doses of IL-2. The combined use may be helpful to improve the treatment regimen by intra arterial injection of IL-2 that we have so far conducted, possibly leading to a higher response rate in clinical setting.