NATURAL-KILLER CELL-MEDIATED CYTOTOXICITY OF BLOOD-LYMPHOCYTES FROM PATIENTS WITH MALIGNANT MESOTHELIOMA TREATED BY INTRAPLEURAL INTERLEUKIN-2

The most impressive biological effect of recombinant Interleukin-2 (rI L-2) is the generation of nonspecific killer cells that have lytic act ivity for a variety of tumor cells. Numerous studies have shown that t hese non specific killer cells might be of NK cell lineage even though they are different from resident NK-cell. We have examined the kineti cs of the NK cell-mediated cytotoxicity of blood lymphocytes in patien ts after intrapleural rIL-2 administered for the treatment of pleural cancer. Escalating doses of rIL-2 were administered by intrapleural ro ute to treat 11 patients with malignant pleural effusions due to malig nant pleural mesothelioma (4 stage I, 4 stage II, 2 stage III, 1 stage IV). Two patients received respectively 3 cycles and 2 cycles of trea tment. Peripheral blood lymphocyte cytotoxicity was assessed by an in vitro, chromium release microcytotoxicity assay against K562 cell line . Preliminary results indicate: (i) an important and prolonged increas e in the cytotoxic response of blood lymphocytes in all patients but o ne having a clinical response and (ii) a lack of cytotoxicity or a bas eline cytotoxic response of blood lymphocytes in all patients but one with no clinical response. These results likely point out the signific ance of NK-activity in the IL-2-induced antitumoral response and the i nterest of this in vitro assay for screening patients for further cycl es of treatment.