Analysis of secondary transplantation in RAG-1^-/- deficient mice 6 to 7 months after transplantation. Six months after primary engraftment, mice were killed and 5 × 10⁶ bone marrow cells were injected into secondary RAG-1^-/- recipients. (A) Leukocyte cell count was 5000 cells/mm³ in the blood, and total cell counts were 4 × 10⁶ cells in the lymph nodes, 11 × 10⁶ cells in the spleen, and 0.2 × 10⁶ cells in the thymus. The dot plots are representative of 1 mouse of 10 that gave similar results. Percentages represent the proportion of cells expressing CD4, CD8, B220, IgM, or IgD markers. (B) Representative immunoscope profiles of TCR Vβ and TCR Vα analysis in the spleen cells of mice undergoing secondary transplantation 6 months after primary transplantation. The x-axis of immunoscope profiles indicates CDR3 length, and the y-axis displays arbitrary fluorescence intensity of the runoff products. (C) Quantification of provirus integration in RAG-1^-/- mice undergoing secondary transplantation. The hRAG1 copy number was determined on the DNA extracted from thymus, spleen, lymph nodes, and bone marrow cells. Data are expressed as means plus or minus SD.