Flow cytometry of engrafted cells in NOD/SCID mice. FACS-sorted CD34⁺CLL-1⁺ cells from 3 different AML patients were transplanted into NOD/SCID mice. Six weeks after transplantation, the mice were killed and engraftment of human cells in these mice was studied using human anti-CD45 labeling. The engrafted cells were analyzed for myeloid origin (CD19⁻ and CD33⁺, data not shown), leukemia-associated phenotype, and CLL-1 expression. Patient numbers are the same as in Figure 4. (A-E) The results of engrafted cells in 1 mouse of 3 that received a transplant of cells from patient 2 are shown. (A) CLL-1 expression on CD34⁺ cells at diagnosis (the CD34⁻ cells in this sample were also CLL-1⁺, not shown). (B) Aberrant expression of CD7 on part of the leukemic CD34⁺ cells at diagnosis. (C) The CD45⁺ human population within the white blood cell compartment of the mouse. (D) The human cells that grew out of the transplanted CD34⁺CLL-1⁺ cells are all CLL-1⁺, similar to the whole blast compartment at diagnosis. (E) Similar to diagnosis, part of the cells again show aberrant CD7 expression. (F,H) The human CD45⁺ population within the white blood cell compartment of mice that received a transplant of cells from patients 3 and 1. CLL-1 expression on engrafted cells is shown in panels G and I.