Antitumor Killer Lymphocytes in the Peripheral Blood of a Patient with Transitional Cell Carcinoma of the Bladder

Background: Peripheral blood lymphocytes (PBL) from patients with bladder cancer also contain cells possessing cytotoxic activity against autologous tumor cells. These cells are phenotypically heterogenous and include natural killer (NK) and cytotoxic T cells. This study investigated the role of cytotoxic lymphocytes directed against autologous bladder cancer cells. Methods: PBL were obtained at intervals before and after surgery and analyzed for cytotoxic activity against autologous bladder cancer cells in 4‐hour51 Cr release assay. PBL stimulated with autologous tumor cells were also transformed with human T‐lymphotropic virus type‐1, establishing a cell line (KB31) which was analyzed for phenotype and cytotoxic activity against the autologous tumor cells. Results: PBL preoperative cytotoxic activity was low, but increased after surgery. Cytotoxic activity was found not only against autologous bladder cancer cells, but also against heterologous bladder cancer (KK‐47) and myeloid leukemia (K562) cells, with the highest activity against the heterologous cell lines. The cytotoxic activity of KB31 was 40|X% against autologous tumor cells 6 weeks after initiation of the cell line, but decreased to 5|X% by 6 months. This activity was lower than that against the other cell lines, and was similar to that of PBL in short‐term culture. Fluorescence‐activated cell sorter (FACS) analysis demonstrated that in KB31 cells at 6 weeks, CD8+ cells were dominant, but CD56+ cells predominated at 6 months. Conclusion: These results suggest that the presence of cytotoxic activity in the peripheral blood of the patient was due to both cytotoxic T cells and NK cells. The cytotoxic activity was lowest prior to surgery and increased postoperatively.