High frequency of T cell clonal expansions in primary human melanoma. Involvement of a dominant clonotype in autologous tumor recognition

Abstract

It was previously found that primary melenomas from HLA-A2-matched patients display an increased expression of a few T cell receptor (TCR) variable-region beta-chain transcripts (BV) compared with autologous peripheral blood lymphocytes (PBL) and uninvolved skin. In order to see whether expansions of clonal/oligoclonal subsets of T cells occurred, complementarity-determining region 3 (CDR3) of BV transcripts overexpressed in the neoplastic infiltrate were cloned and sequenced. Dominant rearrangements were found for BV14, which were commonly increased in the neoplastic lesions of all analysed HLA-A2 melanoma patients, as well as for other overexpressed BV gene families, but none of them could be identified among autologous PBL. No identical CDR3 sequences could be detected in the dominant BV14 rearrangements obtained from the different patients. In one patient a single clonally expanded SLSGTGVNEQF CDR3 clonotype accounted for the entire BV14 relative frequency of expression (24%) in tumor-infiltrating lymphocytes (TIL). Two independent mixed lymphocyte/tumor cultures (MLTC) could be successfully established from TIL of the patient and were found to exert HLA-class-I-restricted cytotoxicity for the autologous melanoma line. BV14 T cells that constituted from 22% to 32% of all T cells present in both MLTC lines, as assessed by flow cytometry, all displayed the same CDR3 clonotype found in vivo and could be shown, by TCR down-modulation experiments, to be involved in autologous tumor recognition. These results support the hypothesis of a tumor-antigen-driven origin of clonally amplified T cells present at high frequency in the in situ neoplastic infiltrate.

Peptide‐specific CD8+ T‐cell evolution in vivo: Response to peptide vaccination with Melan‐A/MART‐1

“…Oligoclonal TCR VB14 expansions were detected in CD3+ CD8+ T cells of 2/3 patients. TCR VB14 has been associated with recognition of autologous melanoma lesions35 and with Melan‐A/MART‐1 specificity 13. However, we have not been able to associate the presence of the TCR VB14 family with Melan‐A/MART‐1 tetramer‐binding T cells, presumably due to the fine tuning of TCR numbers expressed on individual T‐cell clones and CD8 expression required for optimal tetramer binding 20, 21…”

Identification of a public CDR3 motif and a biased utilization of T-cell receptor V beta and J beta chains in HLA-A2/Melan-A-specific T-cell clonotypes of melanoma patients

“…Finally, we looked for very similar sequences at the same CDR3 positions because it is conceivable that these sequences adopt equivalent structures in the recognition complex. We found a Glycine-Valine-Glycine stretch in 8 clonotypes, 5 of which were identified in melanoma patients [[ 4 , 12 , 14 , 30 ] and manuscript in preparation] and 3 in controls [ 3 , 5 ].…”

“…Differently from TRAV, the TRBV repertoire of Melan-A-specific T lymphocytes appears to be large and diverse in terms of clonal composition and TRBV region usage, as multiple clonotypic transcripts, covering the majority of the TRBV families, have been identified in HLA-A2+ patients [ 5 - 7 , 14 , 17 ]. Conversely, other authors reported that the recognition of melanoma Ags involved the use of T lymphocytes bearing specific TRBV chains, such TRBV5, TRBV9, TRBV19, TRBV27, and TRBV28 [ 16 , 18 , 23 , 30 , 35 ]. The different results are likely due to intrinsic limitations imposed by the limited number of patients analyzed and by the fact that the mature TR repertoire is influenced not only by the coding potential of TR VDJ regions, but also by the immunological history of the individuals.…”

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“…Likewise, Pisarra el al., demonstrated tumor specificity and cytotoxic capacity of an in situ expanded TCRBV14 CTL clonotype in a HLA-A2 melanoma patient. As given above, Mart-1 specific CTL predominantly express BV14, however, neither the restriction element nor the peptide was characterized [58]. …”