Competitive grafts with different ratio of KI/WT BM cells showing disease propagation from a low number of KI SLAM cells. (A) Left: composition in WT/KI SLAM (LSK, CD48−, CD150+) cells, determined by FACS analysis, in the 3 × 106 cells grafts mixing different percentages of KI and WT BM cells from 1-month-old donor mice. Right: WBC (106/mL), hematocrit (%), and platelet (109/mL) levels and frequency of blood KI myeloid cells (CD45.2/CD11b/Gr-1) measured 12 and 29 weeks after transplantation of BM samples containing 0%, 1%, 3%, 10%, 30%, 60%, and 100% KI BM cells (n = 5/graft mixture). Results show that a disease may develop (3/5 recipients) from a graft containing 10% KI BM cells or 17 KI SLAM cells. (B) BM cellularity, spleen weight, and Lin-, LSK, and SLAM cells from KI origin found 29 weeks after transplantation in mice transplanted with 0%, 10%, 30%, and 100% KI BM cells. Results show low BM cellularity, splenomegaly, and amplification of early cells from the initial 7% and 21% KI SLAM cell input present in the 10% and 30% KI BM graft. (C) Percent of CD3, B220, and CD11b/Gr-1 cells from KI origin in the blood of mice transplanted with 10%, 30%, 60%, and 100% KI BM cells. Results show that myeloid cells but not lymphoid cells were amplified after transplantation from the initial 7%, 21%, and 49% KI SLAM cell input present in the 10%, 30%, and 60% KI BM graft. Data are mean values ± SEM, n = 5/graft mixture, except for mice grafted with 10% KI cells in graphs B and C, where only 3 mice developed the disease, the 2 other mice having no KI cells detectable 6 months after transplantation. *P ≤ .05 with the 2-tailed unpaired Student t test compared with recipients grafted with 0% KI cells.
