T Cell Receptor - ? and - 6 Genes Preferentially Utilized by Adult Thymocytes for the Surface Expression '

To assess the diversity of y6 receptors expressed on adult thymocytes we characterized the yand 6genes used in a panel of T cell hybridomas expressing a TCR-y6-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 VY4, two used VY7, and one used v,6 for y-genes, and four used Vas. two used Va4. and two used Va7 for &-genes. The last &gene is documented for the first time. V, and V, appear to pair randomly only restricted by the frequency of the utilization of individual V, and V, segments. These yand 6-genes contained N region addition between the V and J region in most cases. Both Dal and Da2 regions were used in the most 6-genes as was seen previously. These results show that certain yand &gene segments that are rarely used for the expression on fetal thymocytes are preferentially used by adult thymocytes. Also the repertoire of the y6 receptors on adult thymocytes is much greater than that on fetal thymocytes. BW5147 specific V4-C1 y-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 y genes, there exists a novel V gene segment-dependent control of transcription in the y-gene system.