Cytotoxic T lymphocytes recognize tumor antigens of a murine colonic carcinoma by using different T-cell receptors

To see whether different antigens expressed by the same tumor are recognized by distinct T-cell receptors (TCR), we used cytotoxic T-lymphocyte (CTL) lines known to lyse in vitro the syngeneic BALB/c adenocarcinoma C-26. Four of these CD3⁺ CD8⁺ lines showed 4 different patterns of lysis on a panel of MHC-class-I-compatible targets. The activity was H-2(d)-restricted and could be blocked by anti-CD3 and anti-TCR-α/β monoclonal antibodies (MAbs). The CTL lines were also effective, although to a different extent, in adoptive immunotherapy of mice bearing lung metastases. Phenotypic analysis revealed in all the lines a high frequency of cells positive for CD45, asialo GMI (ASGMI), lymphocyte-function-associated antigen-I (LFA-I), intercellular adhesion molecule-I (ICAM-I) and CD44, but negligible expression of L- selectin (LAM-I) and very late antigen-4 (VLA-4); 2 lines expressed the vitronectin-receptor (VN-R). Analysis of TCR Vβ-chains used by the 4 lines showed selective presence of Vβ6, Vβ8.2, Vβ8.3 and of Vβ13 chains. MAbs directed to these Vβ chains blocked their lytic activity in vitro. Vα- chain transcripts of the lines were identified by polymerase chain reaction (PCR) as VαITTII and Vα52 in 2 lines, while one could not be identified. Analysis of Vβs in mixed lymphocyte-tumor-cell cultures (MLTC) of T cells deriving from tumor-infiltrating lymphocytes (TIL) or from spleen of C-26 tumor-bearing or immune animals indicated that the TCR of the CTL lines were representatives of the TCR repertoire recognizing C-26 tumor, since their Vβs were shown to be selectively expanded in MLTC.