Induction of Killer Cells from Lymphocytes in Pleural Effusion of Advanced Lung Cancer Patients

We analyzed the phenotype and cytotoxic ability of pleural exudative lymphocytes (PLEL) which were obtained from 18 advanced lung cancer patients. Freshly isolated PLEL were mainly CD4(+) T cells and had weak natural killer, autologous tumor killing and lymphokine‐activated killer activities. After cultivation of PLEL with interleukin‐2, cytotoxicity of PLEL against autologous tumor cells was increased at 2 weeks, but it was remarkably reduced at 4 weeks. When PLEL were stimulated by mitomycin C‐treated autologous tumor cells during culture, autologous tumor killing activity of PLEL was significantly enhanced even after 4 weeks of cultivation. Cold target inhibition analysis and binding inhibition assays using monoclonal antibodies indicated that autologous tumor stimulation could induce major histocompatibility complex class I restricted cytotoxic T lymphocytes specific for autologous tumor cells in some cases.