Lack of TCRγ gene rearrangement in nude mouse NK cells and B6 mouse B cells. (A) Percentages of NK (NK1.1⁺CD3^–) cells and T (NK1.1^–CD3⁺) cells in the spleen of 1-year-old (left) and 3-day-old (right) nude mice. (B) Agarose gel electrophoresis and ethidium bromide staining of genomic PCR (Vγ2-Jγ1) of IL-2–activated and fresh NK cells from adult and neonatal nude mice. T cells that accumulate in aged nude mice were also isolated from spleen of the same adult mouse by cell sorting. Thymocytes were used as positive control and fibroblasts (L cells) were used as negative control. Genomic PCR for a part of Nkg2a gene confirms that comparative amounts of template DNA was used for all the genomic PCR. (C) Southern blot with Jγ1 probe of genomic PCR products generated from IL-2–activated NK cells from adult thymuses and BM and γδ T-cell and fibroblast DNA mixed at various ratios. The middle panel is a longer exposure of the same membrane. The bottom panel shows control Nkg2a PCR confirming that comparable amounts of DNA were used for the analysis. (D) Southern blot with Jγ1 probe of genomic PCR (Vγ2-Jγ1) of B6 adult and neonatal splenic B (CD19⁺CD3^–). Genomic PCR for a part of Nkg2a gene confirms the presence of B-cell DNA.