Characterization of the Functional Specificity of a Cloned T-Cell Receptor Heterodimer Recognizing the MART-1 Melanoma Antigen

T cells can play a central role in the immune response to cancer, with tumor-specific T-lymphocyte reactivity provided by the T-cell receptor (TCR) α and β chain heterodimer. This study is the first report of the definitive identification and characterization of a functional tumor-associated, antigen-specific TCR by reconstitution in an alternate cell line. Jurkat T cells were transfected with the cDNAs encoding the full-length a and 0 T-cell receptor chains from the HLA-A2 restricted, melanoma-reactive T-cell clone, clone 5. Expression of the transfected TCR was evaluated by immunofluorescence after down-modulation of the endogenous receptor with Jurkat T-cell receptor β chain-specific mAb. Jurkat clone 5 TCR⁺ cells recognized MART-1 peptides presented by T2 cells in a pattern and sensitivity equivalent to native MART-1-reactive T-cells. Recognition of HLA-A2+ melanoma cell lines by the Jurkat clone 5 TCR+ cells, however, did not occur without the addition of exogenous MART-1 peptide. The cloning and expression of functional TCR genes which are capable of specifically recognizing MART-1 antigen provides reagents which could be used for the study of the mechanisms of T-cell/tumor antigen interactions and creates immortalized reagents which can facilitate studies requiring detection of the MART-1 antigen. The tumor reactivity provided by these genes could also have application in novel immu-notherapeutic strategies for treating patients with melanoma, including redirection of tumor-infiltrating lymphocyte specificity and bone marrow stem cell therapy.