Use of the Vδ1 Variable Region in the Functional T‐Cell Receptor α Chain of a WT31+ Cytotoxic T Lymphocyte Clone which Specifically Recognizes HLA‐A2 Molecule

We report here the molecular characterization of the T-cell receptor (TCR) expressed by a human HLA-A2 specific cytotoxic T-cell clone named CTL 49. Flow cytometry analysis with a panel of and-TCR antibodies revealed an OKT3+, WT31+, A13+, BB3-, TCRδri-, δTCS1-, TCRγ/δ1-, OKT4-, and OKT8+ phenotype, suggesting that, in CTL 49, the Vδ1 -encoded A13 epitope could be included in its α/β TCR. Northern blot analysis confirmed the presence of Cα, Cβ and Vδ1 specific transcripts while no hybridization signal was detected by a Cδ specific probe. Polymerase chain reaction (PCR) amplification of the first strand cDNA from CTL 49 with TCR-specfic primers and sequence analysis revealed that Vδ1 region is productively rearranged Jα and to Cα regions. This α chain pairs with a β chain composed of Vβ13.2/Dβ/Jβ2.3/Cβ2 leading to the expression of a functional TCR complex. These results, in addition to providing further evidence for the sharing of Vδ1 by α/β and γ/δ TCR, indicate that an α/β T-cell receptor which includes the Vδ variable region can be involved in alloreactive recognition.