P1CTL nu/nu bone marrows do not have mature transgenic T cells. One-month-old P1CTL nu/nu bone marrow cells were stained with anti-CD8, anti–Vα8.3 TCR, or isotype controls. WT P1CTL bone marrow was used as positive control. Data indicate a complete lack of T cells in the P1CTL⁺ nu/nu bone marrow.