CYTOTOXIC T-LYMPHOCYTE CLONES FROM DIFFERENT PATIENTS DISPLAY LIMITED T-CELL-RECEPTOR VARIABLE-REGION GENE USAGE IN HLA-A2-RESTRICTED RECOGNITION OF THE MELANOMA ANTIGEN MELAN-A/MART-1

To determine whether T-cell-receptor (TCR) usage by T cells recognizing a defined human tumor antigen in the context of the same HLA molecule is conserved, we analyzed the TCR diversity of autologous HLA-A2-restricted cytotoxic T-lymphocyte (CTL) clones derived from five patients with metastatic melanoma and specific for the common melanoma antigen Melan-A/MART-1. These clones were first identified among HLA-A2-restricted anti-melanoma CTL clones by their ability to specifically release tumor necrosis factor in response to HLA-A2.1(+) COS-7 cells expressing this tumor antigen, A PCR with variable (V)-region gene subfamily-specific primers was performed on cDNA from each clone followed by DNA sequencing, TCRAV2S1 was the predominant alpha-chain V region, being transcribed in 6 out of 9 Melan-A/MART-1-specific CTL clones obtained from the five patients. beta-chain V-region usage was also restricted, with either TCRBV14 or TCRBV7 expressed by all but one clone. In addition, a conserved TCRAV2S1/TCRBV14 combination was expressed in four CTL clones from three patients, None of these V-region genes was found in a group of four HLA-A2-restricted CTL clones recognizing different antigens (e.g., tyrosinase) on the autologous tumor, TCR joining regions were heterogeneous, although conserved structural features were observed in the complementarity-determining region 3 sequences, These results indicate that a selective repertoire of TCR genes is used in anti-melanoma responses when the response is narrowed to major histocompatibility complex-restricted antigen-specific interactions.