Use of the Vδ1 variable region in the functional T-cell receptor α chain of a WT31+ cytotoxic T lymphocytes 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 anti-TCR antibodies revealed an OKT3⁺, WT31⁺, A13⁺, BB3^-, TCRδ^-, δTCS1^-, TCRγδ1^-, 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 rection (PCR) amplification of the first strand cDNA from CTL 49 with TCR-specific primers and sequence analysis revealed that Vδ1 region is productively rearranged to Jα and to Cα regions. This α chain pairs with a β chain composed of Vβ 13.2/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 Vδ1 variable region can be involved in alloreactive recognition.