Isolation of Tumor-Specific Cytotoxic CD 4 1 and CD 4 1 CD 8 dim 1 T-Cell Clones Infiltrating a Cutaneous T-Cell Lymphoma

We have isolated several T-cell clones from lymphocytes infiltrating a human major histocompatibility class (MHC) II negative cutaneous T-cell lymphoma (CTCL). We describe here two of these clones, TC5 and TC7, with, respectively, a CD41CD8dim1 and CD41CD82 phenotype. 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 interleukin-2 (IL-2) and IL-7 from the skin and from the blood. Analysis of the T-cell receptor (TCR) Vb gene expression showed that the tumor cells, which were shown to have a trisomy 7 by fluorescent in situ hybridization, expressed Vb7/Jb2.3, Vb13/ Jb2.5, and Vb22/Jb2.5 rearrangements. Phenotypic analysis using specific anti-Vb monoclonal antibodies indicated that only Vb13 could be detected on the cell membrane of the tumor cells. Analysis of the TCR Vb gene expression of the clones showed that TC5 and TC7 expressed a unique TCR-Vb transcript, corresponding, respectively, to Vb5/Jb2.3 and Vb17/Jb2.7 gene segments. To determine whether these reactive T lymphocytes were present in vivo, we used specific primers corresponding to TC5and TC7-Vb TCR transcripts. The results showed 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 show for the first time the presence of reactive T lymphocytes with CD4 or doublepositive phenotype infiltrating a CTCL. These findings raise the question of the role of these antitumoral effector T cells in the tumor growth. r 1998 by The American Society of Hematology.