Interleukin (IL-)15 has less activity than IL-2 to promote type 2 cytokine predominance in tumour-associated mononuclear cells from lung cancer patients.

Deviation of type 1/type 2 cytokine balance to type 2 predominance may contribute to tumour progression. We investigated effect of interleukin (IL-)15 on modulation of type 1/type 2 balance in addition to non-major histo-compatibility complex (MHC)-restricted killer induction in the tumour-growing site. IL-15 induced significant killer activity in mononuclear cells (MNC) in malignant pleural effusion as well as those in peripheral blood. Pleural MNC produced more IFN-gamma (type 1 cytokine) by incubation with IL-15 or IL-2 than blood MNC. Moreover, IL-4 and IL-5 (type 2 cytokines) production by pleural MNC were observed only by incubation with IL-2, but not with IL-15. These observations suggest that IL-15 has a potent activity to restore type 1/type 2 balance in addition to killer induction in tumour-growing site.