Cloning of the gene encoding the delta subunit of the human T-cell receptor reveals its physical organization within the alpha-subunit locus and its involvement in chromosome translocations in T-cell malignancy.

By taking advantage of "chromosomal walking" techniques, we have obtained clones that encompass the T-cell receptor (TCR) delta-chain gene. We analyzed clones spanning the entire J alpha region extending 115 kilobases 5' of the TCR alpha-chain constant region and have shown that the TCR delta-chain gene is located over 80 kilobases 5' of C alpha. TCR delta-chain gene is rearranged in the gamma/delta-expressing T-cell line Peer and is deleted in alpha/beta-expressing T-cell lines. Sequence analysis of portions of this genomic region demonstrates its identity with previously described cDNA clones corresponding to the C delta and J delta segments. Furthermore, we have analyzed a t(8;14)-(q24;q11) chromosome translocation from a T-cell leukemia and have shown that the J delta segment is rearranged in cells deriving from this tumor and probably directly involved in the translocation. Thus, the newly cloned TCR delta chain is implicated in the genesis of chromosome translocations in T-cell malignancies carrying cytogenetic abnormalities of band 14q11.