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) alpha and beta 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 alpha and beta 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 beta 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 immunotherapeutic strategies for treating patients with melanoma, including redirection of tumor-infiltrating lymphocyte specificity and bone marrow stem cell therapy.