Characterization of adult ALL xenografts. (A) Comparison of flow cytometric analysis of original ALL from UPN 21 (gray dashed) and resulting leukemia xenograft from BM of mouse 62862 (black) showing down-regulation of CD24, CD123, and CD58 expression. CD19⁺/CD34⁺ gates are presented. (B) Schematic of clonal Ig/TCR rearrangements in the original sample (non-color highlighted text) compared with the xenografted leukemia. Ig/TCR rearrangements that are preserved (blue), lost (red), or newly emergent (green) in leukemia xenografts are color highlighted. *Newly emergent VH1 clone accompanied loss of the original VH1 rearrangement in this xenograft. (C) Heteroduplex gel images of PCR-amplified Ig/TCR rearrangements in BM from 2 leukemic mice (154 and 155), both transplanted with cells from UPN 14 showing differences in clonal composition between engrafted leukemias. Preservation (blue box) and loss (red box) of original rearrangements and newly emergent clones (green box) are indicated. (D) Newly emergent VH6 clones (highlighted green) in xenografts share identical DH-N-JH stems (gray box) with rearrangements that predominated in the original sample (highlighted blue), indicating that clonal evolution by variable (VH) gene addition to preexisting DH-JH rearrangements had occurred in the respective human tumor.