Peripheral blood and tumor infiltrating lymphocytes in non-small cell lung cancer: analysis at the population and clonal level

Tumor infiltrating (TIL) and peripheral blood lymphocytes (PBL) were isolated from 18 patients with non-small cell lung cancer undergoing radical surgery. Surface marker analysis revealed that TILs and PBLs mainly consisted of CD3+ T cells and that TILs generally displayed a lower CD4/CD8 ratio. Differences were found in the expression of CD25 (IL-2 receptor) and DR (MHC class II) antigens, which were increased in TILs, and in the percentage of CD16+ natural killer (NK) cells, which was reduced in TILs as compared to PBLs. Accordingly, the NK activity of TILs was lower than that of PBLs, whereas neither TILs nor PBLs expressed spontaneous cytolytic activity against fresh autologous tumor cells, melanoma cells and the "NK-resistant" A549 lung carcinoma cell line. After 4 days of culture in medium with recombinant-interleukin-2 (rIL-2), TILs and PBLs acquired cytolytic activity against all cell targets, but TILs expressed higher levels of cytotoxicity than autologous PBLs only in 3 patients out of 16 tested. More importantly, both TILs and PBLs displayed similar levels of cytotoxic activity against autologous tumor cells. TILs and PBLs from 8 patients were also analyzed by a limiting dilution microculture system. Cloning efficiency was remarkably lower in TILs, and surface marker analysis of T cell clones confirmed that an accumulation of CD8+ lymphocytes, which displayed cytolytic activity in a lectin-dependent assay, occurred at the tumor site. The non-MHC-restricted cytolytic activity of TIL- and PBL-derived T cell clones against K562, A549, and allogeneic melanoma cells and the cytolytic activity against autologous tumor cells showed no significant differences. Only 53% of TIL clones released IL-2 in response to PHA + TPA stimulation, whereas 68% of PBL-derived clones were IL-2 producers. Moreover, most PBL- and TIL-derived clones released tumor necrosis factor alpha in response to mitogen stimulation.