IGH rearrangement analysis shows oligoclonal expansion from LICs and polyclonal expansion from CD34⁺CD38⁻CD19⁻CD33⁻ cells. (A) In MLL-AF4 case 3, PCR for IGH rearrangements showed the presence of a dominant clone present in CD34⁺ and CD34⁻ cells, regardless of CD33 expression. (B) IGH rearrangement patterns of 4 engrafted cell populations from recipients of CD34⁺CD38⁻CD19⁻CD33⁺ LICs (left column of panels), CD34⁻CD19⁺ LICs (second and third columns of panels), and CD34⁺CD38⁻CD19⁻CD33⁻ cells (right column of panels) isolated from MLL-AF4 case 3. Shared dominant clones were detected in (left) CD34⁺CD38⁺CD19⁺ cells from recipient 1-32 engrafted with CD34⁺CD38⁻CD19⁻CD33⁺ LICs, and (second from left) CD34⁺ and (third from left) CD34⁻ cells from recipient 1-18 engrafted with CD34⁻CD19⁺ LICs. In contrast, CD19⁺CD33⁻ B cells in recipient N1-1 engrafted with CD34⁺CD38⁻CD19⁻CD33⁻ cells from MLL-AF4 case 3 (right column) show polyclonal pattern of IGH rearrangement.