Comparison of cytotoxic activity between TIL isolated from rat osteosarcomas and autologous PBL. TIL were isolated from rat osteosarcoma biopsies (n = 8). After 14 days of culture in X-VIVO 15 supplemented with 900 UI/ml IL-2, TIL and autologous PBL cytotoxic activities were determined using 51Cr-released assays. The cytotoxicity was measured against autologous rat osteosarcoma cells and allogeneic rat osteosarcoma cell lines including UMR 106 and ROS 17/2.8. * p < 0.05, TIL versus PBL cytotoxicity.