Catherine Genevée

TCR gene segments from at least one third of Va subfamilies rearrange at the δ locus

Using PCR and an experimentally validated V alpha subfamily-specific oligonucleotide panel (V alpha 1-w29), we have investigated whether the TCR delta chain may increase its combinatorial diversity by using V genes considered as alpha chain-specific. We show that at least 10 distinct human V alpha segments rearrange at the J delta locus, leading to scrambling of the two V gene repertoires. Fifty-five per cent of the V alpha/J delta transcripts characterized here were in frame. The 17 V alpha/C delta chains analysed included an extended CDR3 region with up to 18 aa encoded by the junctional region. In addition, a new J delta segment (J delta 4) has been characterized. Together, these findings demonstrate that combinatorial diversity in the human delta locus is larger than previously thought.

CD3.TCR1, A Human CD3 epitope expressed on viable γδ lymphocytes exclusively

Abstract T lymphocytes express either the α β or the γ δ receptor (TCR) in a mutually exclusive fashion. Both structures are associated on the cell membrane with the CD3 proteins which are thought to transduce signals resulting from antigen recognition. The CD3 complex is present in both γ β and γ δ cells and includes at least five proteins (designated γ, δ, ϵ, ξ and η). We have developed here a novel mAb, anti-CD3.TCR1, which immunoprecipitates the CD3 molecules from both γ β and γ δ cells lysates following solubilization with Triton X-100. While the SDS-PAGE migration profile of the material recognized by either anti-CD3.TCR1 or anti-OKT3 are superimposable in both cell types, this mAb recognizes viable untreated γ δ T lymphocytes exclusively. These findings further support the view that molecular interactions within the TCR CD 3 protein complex are distinct in the two T lymphocyte populations.

The T-cell receptor Vδ genes predominantly used by human peripheral γ/δ+ T lymphocytes are not rearranged in CD3− natural killer cells

Abstract We have analyzed, in 19 CD3 − natural killer cells clones, the genomic organization of the T-cell receptor δ locus with two distinct Vδ probes, Vδ1 and Vδ2. These two Vδ genes code for surface proteins expressed in more than 90% of peripheral blood T-cell receptor γ/δ + lymphocytes, as shown by double color immunofluorescence analysis with anti-TCRδ1, anti-BB3, and anti-δTCS1 monoclonal antibodies. The Vδ1 and Vδ2 genes were found to be in germline position in all these clones, which are distinct phenotypically and represent a variety of the corresponding peripheral natural killer cell populations. We also studied in these cloned cell lines the transcriptional activity of the T-cell receptor δ locus with a Cδ probe: short transcript (1.7 and 0.8 kb) were found exclusively. These experiments further suggest that CD3 − natural killer peripheral cells are likely to constitute a unique lineage distinct from T lymphocytes.