Southern blot analysis of TCRδ and TCRγ gene rearrangements. The schematic diagrams of the germline configuration of the human TCRδ (A) and TCRγ (D) genes show the position of the TCRDJ1 and Jγ1.3 probes, respectively. Exons and pseudo genes are depicted as solid and open boxes, respectively. (B and E) Southern blot analysis of filters containing EcoRI-digested DNA of HeLa cells (lane 1), six human thymocyte subpopulations (lanes 2 to 7), and total human thymocytes (lane 8) hybridized with the TCRDJ1 and Jγ1.3 probes, respectively. Rearranged bands were assigned based on the size of the bands.21 33 Rehybridization of the filters with the IGKDE probe was performed as a control for loading of the lanes (C and F). G and R indicate germline and as yet unidentified rearrangements, respectively. (a) Underdigestion of the DNA leads to two additional bands in the control DNA. (b) Band caused by plasmid contamination.