Interleukin-4 inhibits lak and initial phase til activity via interleukin-2 receptor

In the present study, we analyzed the proliferation and cytotoxic activities of LAK cells and initial phase TILs by stimulation with IL-4. IL-4 obviously inhibited the DNA synthesis of LAK cells and initial phase TILs at the concentration of 250 pg/ml and 25 pg/ml, respectively. Furthermore, IL-4 (25 ng/ml for LAK cells, 25 pg/ml for initial phase TILs) suppressed the cytotoxic activities against K562, KATO-III, and autologous tumor cells. The discrepancy of the concentration between the proliferation and the cytotoxicicity by IL-4 suggested different pathways in terms of the generation of LAK cells. In order to clarify the inhibitory mechanism of IL-4, we measured the expression of IL-2 receptor. IL-2 receptor alpha chain was strongly down-regulated by IL-4. Thus, IL-4 modulates the activation of LAK cells and initial phase TILs via the IL-2 receptor alpha chain.