Cellular immune response to human sarcomas: cytotoxic T cell clones reactive with autologous sarcomas. I. Development, phenotype, and specificity.

Human T cell clones cytotoxic for autologous sarcoma cell lines have been developed from patient JM with an osteogenic sarcoma, and from patients EG and RM with malignant fibrohistiocytoma. These clones were derived from the cocultivation of peripheral blood lymphocytes (PBL) with the respective patient's autologous irradiated established tumor cell lines (AIT). After two cycles of stimulation for 5 days in bulk culture, these "educated" lymphocytes were seeded at a density of 1 X 10(6) cells/well in 24-well plates and were cultured in the presence of highly purified natural IL 2 and AIT, the latter serving as a feeder layer. Cell numbers were reduced from the initial seeding density by one log each week until reaching a density of 10(2) cells. These cells were found to be stable in viability and cytotoxic activity, after which limiting dilution was then performed. Within 4 to 6 wk, clones were isolated with unique specificities. These clones were capable of proliferating to a total density of 10(9) cells/ml and maintained their specific cytotoxicity for more than 6 mo. Testing with a panel of target cells of various histotypes, cold-target inhibition assays, and blocking of cytotoxicity with anti-HLA monoclonal antibodies showed that the T cell clones recognize a common sarcoma-associated antigen and that the lysis is HLA restricted. Phenotypically, cytotoxic clones derived from JM were Leu-1+, Leu-2+, and Leu-3-, whereas those derived from EG exhibited either Leu-24 or Leu-3+ markers, the latter phenotype lacking cytotoxicity. RM exhibited mainly Leu-3+ clones with strong cytotoxicity. All were HNK-1- and HLA class II+, with less than 1% of cells of each clone stained by anti-TAC monoclonal antibody. The clones from each patient did not lyse autologous or allogeneic PBL, mitogen-induced T lymphoblasts, normal fibroblasts, cells isolated from benign neoplasms, carcinoma cells, Daudi B lymphoid cells, or K562 cells. With the exception of EG, all clones produced immune interferon in a range from 12 to 50 U/ml. The generation of long-term specific T cell clones can be used to further dissect the cellular immune response to sarcomas. Cytotoxic T cell clones have potential application for tumor immunotherapy.