A transcriptional enhancer of the mouse T cell receptor delta gene locus.

T cells express receptors for antigen on their surface (TcR) which consists either of alpha/beta or of gamma/delta polypeptide chains. Since the TcR delta chain gene is located within the TcR alpha chain gene locus, strict regulation of expression of the region must operate to ensure that the two loci are not concomitantly expressed in T cells bearing either alpha/beta or gamma/delta TcR. In this report it is demonstrated that elements within the mouse TcR delta gene locus, located between the J delta 2 and C delta exons, enhance transcription from a heterologous promoter five- to tenfold in a T cell hybridoma expressing a TcR gamma/delta, whereas enhancement was only twofold in an alpha/beta-bearing T cell hybridoma. No enhancement of expression was observed in a B cell hybridoma. The sequences responsible for this enhancing activity are largely confined to a 766-bp Hae III DNA restriction fragment. A region within this DNA segment shows significant homology (73% identify) to a recently identified enhancer of the human TcR delta gene locus.