GENERATION OF CYTOTOXIC T-LYMPHOCYTES FROM PERIPHERAL-BLOOD

Background. Cytotoxic T lymphocytes (CTL) have been shown to be useful for adoptive immunotherapy in malignancy. Traditional sources for CTL , such as tumor-infiltrating lymphocytes, have limitations. It would t herefore be useful to develop a method of generating antitumor CTL fro m a renewable source such as peripheral blood. Methods. DBA/2 mice wer e injected intradermally in the abdominal wall with the murine tumor P HS-5 and killed 14 days later. Peripheral blood lymphocytes were harve sted and cultured with 20 units/ml interleukin-2 and autologous tumor- stimulator cells treated with mitomycin C. Cultures were split when gr eater than 2 X 10(6) cells/well, fed every 3 days and stimulated weekl y. Results. Lymphocytes expanded greater than 130,000-fold during 8 we eks. Specific cytotoxicity was shown with Cr-51 release assay. Withdra wal of repeated stimulation with autologous tumor resulted in failure of cells to expand in culture and loss of cytotoxicity. In vivo admini stration showed marked reduction of 10-day liver metastases, indicatin g therapeutic efficacy. Conclusions. These data demonstrate a successf ul animal model of adoptive immunotherapy with CTL generated from peri pheral blood lymphocytes.