GENERATION OF KILLER ACTIVITY BY INTERLEUKIN-12 OF MONONUCLEAR-CELLS IN MALIGNANT PLEURAL EFFUSIONS DUE TO LUNG-CANCER

In the present study, we examined the ability of interleukin (IL)-12 t o generate an antitumor effect in the tumor-growing site. Mononuclear cells (MNC) were obtained from 12 malignant pleural effusions due to l ung cancer in the tumor-growing site. Non-major-histocompatibility-com plex-restricted killer activity, examined by 4-h Cr-51 release assay a gainst Daudi lymphoma cells as well as various lung cancer cell lines (H69 and PC-9), and in vitro production of interferon gamma (IFN gamma ), measured by enzyme immunoassay, were investigated as mediators of a ntitumor effects of host cells activated by IL-12. IL-12 induced kille r activity of MNC in pleural effusions (pleural MNC) dose-dependently. Moreover, pleural MNC produced a signficant amount of IFN gamma in re sponse to IL-12. The killer activities of IL-12-activated blood MNC we re higher than those of pleural MNC. The supernatants of pleural effus ions of these untreated patients suppressed killer induction by IL-12 of blood MNC of healthy volunteers. These observations suggest that MN C present at the site of growing tumors may act as effector cells agai nst lung cancer in the presence of IL-12.