RESTORATION OF THE IMMUNOCOMPETENCE BY IL-2 ACTIVATION AND TCR-CD3 ENGAGEMENT OF THE IN-VIVO ANERGIZED TUMOR-SPECIFIC CTL FROM LUNG-CANCER PATIENTS

The present study investigates the nature of the immunosuppressed stat e of the lymphocytes obtained from the malignant pleural effusion (eff usion associated lymphocytes, EAL) of lung cancer patients. The immuno competence of EAL from 13 patients was assessed by determining their T -helper cell phenotype, proliferative response to alpha CD3-activation , and their cytolytic activity against three tumor targets: the autolo gous tumor, Daudi, and K562. Flow cytometry analysis showed that the l ymphocytes in EAL were predominantly T cells with <1% natural killer c ells. The T-helper cell phenotype was found to be predominantly of Th2 type, but could be readily converted to Th1 type by culturing the EAL in vitro, and this conversion was augmented by interleukin-2 (IL-2) o r IL-2 plus alpha CD3. To test the cytolytic activity of EAL, it was f ound that after 6-day culturing, the EAL remained in an immunosuppress ed state so that they failed to kill any of the three tumor targets. S timulation with IL-2 partially restored the immunocompetence of EAL. F urther engagement of TCR-CD3 by alpha CD3 fully restored the cytolytic activity of the EAL to kill the autologous tumor target but not Daudi or K562 tumor cells, and thus seemed to be tumor specific. The specif icity was further confirmed by testing the activating EAL and normal d onor peripheral blood lymphocytes against a variety of tumor targets a nd control targets. Furthermore, the killing by EAL against the autolo gous tumor targets seemed to be major histocompatibility complex-restr icted and was inhibited by anti-human leukocyte antigen class I antibo dy. The EAL from lung cancer patients also showed much reduced respons iveness to the alpha CD3 stimulation to induce proliferation, and addi tion of IL-2 restored the responsiveness. These results suggest that, through close contact with tumor cells, anergy of cytotoxic T lymphocy tes (CTLs) was induced in vivo at a localized site. IL-2 stimulation a nd TCR-CD3 engagement could reverse the anergic state and restored the full competence of CTLs in EAL to mediate the specific anti-tumor kil ling against the autologous tumor. Proper manipulation of EAL may prov e useful as a source of anti-tumor effectors for cancer adoptive immun otherapy.