Isolation of tumor-specific cytotoxic CD4+ and CD4+CD8dim+ T-cell clones infiltrating a cutaneous T-cell lymphoma

We have isolated several T cell clones from lymphocytes infiltrating a human MHC class II negative cutaneous T cell lymphoma (CTCL). Two of diese clones, TC and TC7, with respectively a C+CD8dim+and CD4+CD8dim+andCD4+CD8- phenotype were further studied. Both clones mediated a specific MHC class I-restricted cytotoxic activity toward the fresh autologous tumor cells, and autologous tumor cell lines previously established with IL-2 and IL-7 from the skin and from the blood. Analysis of the T-cell receptor (TCR) Vβ gene expression revealed that the tumor cells, that were shown to have a trisomy 7 by fluorescent in situ hybridization, expressed Vβ7/Jβ2.3, Vβ13/Jβ2.5 and Vβ22/Jβ2.5 rearrangements. Phenotypic analysis using specific anti-Vβ monoclonal antibodies indicated that only Vβ13 could be detected on the cell membrane of the tumor cells. Analysis of the TCR Vβ gene expression of the clones showed that TC5 and TC7 expressed a unique TCR-Vβ transcript, corresponding respectively to Vβ5/Jβ2.3 and Vβ17/Jβ2.7 gene segments. To determine whether these reactive T lymphocytes were present in vivo, we used specific primers corresponding to TC5 and TC7-Vβ TCR transcripts. The results demonstrated that both cytotoxic T cell clones were present at the lesional skin site and amplified in vitro. TC7 was found in the patient peripheral blood invaded by tumoral cells, whereas TC5 was not, indicating that the repertoire of the reactional lymphocytes differs in the blood and at the tumor site. These results demontrate for the first time the presence of reactive T lymphocytes with CD4 or double positive phenotype infiltrating a CTCL. These findings raise the question of the role of these anti-tumoral effector T cells in the tumor growth.