Second transplantation of donor-derived HSC in first recipients (16 weeks).

(A) Expression of c-Kit and CD34 on Ly-5.2⁺Lin⁻ BM cells of the primary recipient mice (Ly-5.1) engrafted with 1 × 10³ neonatal Lin⁻c-Kit⁺CD34^high BM cells (Ly-5.2) 16 weeks after transplantation. Lin⁻c-Kit⁺ cells were fractionated into CD34⁻ (R1), CD34^low (R2), and CD34^high (R3) cells on the basis of CD34 expression. The averages of the proportions of the 3 fractions in Lin⁻c-Kit⁺ cells (n = 3) are shown in each window. (B) The percentages of Ly-5.2⁺ cells in B220⁺ cells (B), Thy-1⁺ cells (T), and Gr-1/Mac-1⁺ cells (M) in Ly-5.1 secondary recipient PB 8 to 10 weeks after the second transplantation. The secondary recipients were transplanted with CD34⁻ (R1), CD34^low(R2), and CD34^high (R3) cells (2 × 10³[○] and 1 × 10⁴ cells [■]) from BM of the primary recipients (Ly-5.1). (C) A representative PB profile of a secondary recipient (Ly-5.1) engrafted with 1 × 10³Lin⁻c-Kit⁺CD34⁻ cells (R3) sorted from the first recipient. Ly-5.2⁺ cells were present in B220⁺ cells, Thy-1⁺ cells, and Gr-1/Mac-1⁺ cells in the PB.