A naw gene coding for a differentiation antigen recognized by autologous cytolytic T lymphocytes on HLA-A2 melanomas
- P. G. Coulie, V. Brichard, +9 authors T. Boon
- J. Exp. Med.,
Renal cell carcinoma (RCC) is one human tumor to which the immune response may control the growth of tumor cells. These tumors are infil trated by a large mononuclear infiltrate mainly composed of T lympho cytes. To characterize the lymphocytes infiltrating RCC, we analyzed the molecular structure of the T cell receptor (TCR) a and ÃŸchains in tumor and paired peripheral blood lymphocytes from a series of 6 untreated patients. We first determined Va and VÃŸgene segment usage by PCR using a panel of V specific oligonucleotide primers (Val-w29 and V/ÃŒIw24). A highly diverse usage of TCR Va and VÃŸgene usage was observed in 5 of 6 tumors. In addition, the few tumor overexpressed VÃŸspecificities detected by reverse transcription-PCR were shown to contain minor T cell expansions. Strikingly, 1 of the 6 tumor studied displayed a skewed TCR repertoire with VÃŸ4transcript representing 25% of the TCR signals. Clonality of the tumor overexpressed VÃŸtranscripts was analyzed by CDR3 size distribution analysis. In the particular tumor displaying a biased repertoire large expansions of T cell subpopulations were detected (particularly in VÃŸ4)specifically at the tumor site. Such T cells may be expanded locally in response to tumor antigens. antibody-like structure. CDR regions 1, 2, and 3 have accordingly been defined for TCR molecules (11). CDR3 regions are encoded by the hypervariable V-J or V-D-J junctions and are essential for binding to the antigenic peptide. The expression of unique rearranged TCR gene products determines the specificity of a given T cell (12). Identification of recurrent TCR transcripts (same CDR3) in T cell populations indicates antigen driven expansion of the corresponding T cells. Thus, the direct analysis of the molecular structure of TCR polypeptides expressed by TIL is one way to study how tumor cells modulate the T cell repertoire. Using different PCR approaches, we analyzed in situ the fine molecular structure of TCR a and ÃŸchains in TIL and paired PBL from 6 RCC patients. A highly diverse repertoire was found in 5 of 6 tumors, whereas it was strongly skewed in the last tumor. Dramatic clonal expansions of few T cell subsets were indeed identified in the last patient. Such data strengthen the view that antigen driven T cell expansion may occur locally and contribute to the control of the tumor evolution at least in some RCC.