TCR GENE SEGMENTS FROM AT LEAST ONE-3RD OF V-ALPHA SUBFAMILIES REARRANGE AT THE DELTA LOCUS

Using PCR and an experimentally validated Va subfamily-specific oligon ucleotide 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 scra mbling of the two V gene repertoires. Fifty-five per cent of the V alp ha/J delta transcripts characterized here were in frame. The 17 V alph a/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 seg ment (J delta 4) has been characterized. Together, these findings demo nstrate that combinatorial diversity in the human delta locus is large r than previously thought.