Comparison of cytotoxic activity between TIL isolated from human osteosarcomas and autologous PBL. TIL and autologous PBL were isolated from human osteosarcomas (n = 6). After 21 days of culture in RPMI 1640 supplemented with 10% FCS and 300 UI/ml IL-2, TIL and autologous PBL cytotoxic activities were determined using 51Cr-released assays. The cytotoxicity was measured against allogeneic cell lines including Daudi, K562 cell lines and two osteosarcoma cell lines, high (SaOS2) and low (MG63) osteoblastic differentiated osteosarcoma. ** p < 0.01; *** p < 0.001, TIL versus PBL cytotoxicity.