Interleukin-12-mediated killer activity in lung cancer patients

The authors investigated the interleukin (IL)-12-inducible killer activity of blood mononuclear cells (MNC) from 30 untreated primary lung cancer patients and 24 control subjects. Cytotoxicity was assayed as 4-h 51Cr release from Daudi lymphoma cells or lung cancer cells (H-69, N-291 and PC-9). MNC from lung cancer patients exhibited similar killer activity to those from control subjects after in vitro incubation with IL-12 for 4 days. Effective killer induction by IL-12 was observed even in MNC from advanced lung cancer patients and patients with small cell lung cancer. IL-12 and a suboptimal dose of IL-2 had additive effects in inducing killer activity in MNC from both lung cancer patients and control subjects. On the other hand, with an optimal dose of IL-2, IL-12 suppressed killer induction. Addition of IL-12 alone or in combination with IL-2 resulted in interferon (IFN)-gamma production by MNC from lung cancer patients as well as control subjects. These observations suggest that IL-12 could be useful for immunotherapy of lung cancer in humans.