T cell receptor-gamma and -delta genes preferentially utilized by adult thymocytes for the surface expression

To assess the diversity of gamma delta receptors expressed on adult thymocytes we characterized the gamma- and delta-genes used in a panel of T cell hybridomas expressing a TCR-gamma delta-CD3 complex on the cell surface. DNA cloning and sequencing analysis were necessary to determine the used genes because of the presence of multiple rearrangements in these hybridomas. Among eight hybridomas analyzed, five used V gamma 4, two used V gamma 7, and one used V gamma 6 for gamma-genes, and four used V delta 5, two used V delta 4, and two used V delta 7 for delta-genes. The last delta-gene is documented for the first time. V gamma and V delta appear to pair randomly only restricted by the frequency of the utilization of individual V gamma and V delta segments. These gamma- and delta-genes contained N region addition between the V and J region in most cases. Both D delta 1 and D delta 2 regions were used in the most delta-genes as was seen previously. These results show that certain gamma- and delta-gene segments that are rarely used for the expression on fetal thymocytes are preferentially used by adult thymocytes. Also the repertoire of the gamma delta receptors on adult thymocytes is much greater than that on fetal thymocytes. BW5147 specific V4-C1 gamma-gene was expressed in all of the adult hybridomas. Inasmuch as this gene was not expressed in BW5147 cells or in fetal thymocyte hybridomas expressing V5 or V6 gamma genes, there exists a novel V gene segment-dependent control of transcription in the gamma-gene system.