Experimental design. (A) Autologous transplantation of retrovirally transduced CD34⁺ cells. Animals were given G-CSF + SCF for 5 days to mobilize CD34⁺ cells into the peripheral blood, and the cells were collected by leukapheresis. Purified CD34⁺ cells were transduced with either G1Na or LNL6 retroviral marking vectors.¹⁵  (B) Transduced CD34⁺ cells were reinfused into the monkeys after 500 cGy = 2 TBI. Animals were then followed after engraftment for at least one year before entry into the current studies. Each animal was treated with 4 mg/kg busulfan intravenously. Granulocytes and lymphocytes were collected at multiple time points before and after busulfan, and used for LAM-PCR analysis. iv indicates intravenously.