Leukemic stem cell accumulation and clonal expansion of T-lymphoma cells in serial ZNF198-FGFR1 transplantation recipients. (A) Schematic illustration of the experimental approach of serial transplantation of BM cells from primary leukemic mice. (B) Kaplan-Meier survival analysis of serially transplanted ZNF198-FGFR1 mice. The difference in survival between primary (1st BMT, n = 10), secondary (2nd BMT, n = 17), and tertiary (3rd BMT, n = 14) recipients is significantly different (P < .05, log-rank test). (C) Flow cytometric analysis of lineage-positive depleted BM cells shows hematopoietic stem cells (Lin⁻ Sca-1⁺ c-Kit⁺) from normal BALB/c mice and leukemic stem cells (GFP⁺ Lin⁻ Sca-1⁺ c-Kit⁺) from ZNF198-FGR1 recipients (left panel). The remarkable accumulation of leukemic stem cells was seen in primary and tertiary ZNF198-FGFR1 recipients (right panel). (D) Schematic representation showing the relative location of the PCR primers used to analyze the TCR locus (top panel). Gel electrophoresis of PCR products with 3 different sets of primers shows DJ arrangement of TCRβ in 2 representative serially transplanted ZNF198-FGFR1 mice (bottom panel). DNA from BM displays only one large band using either D1–Jβ1.6 or Dβ2–Jβ2.6 primer sets, reflecting no rearrangement. DNA from normal thymus (Thy), spleen (SP), and LN shows several smaller bands resulting from rearrangements between different Dβ1 and Jβ2.6 positions. In contrast, DNA from leukemic mouse BM, Thy, and SP shows only one or a few bands. Specifically, when using the Dβ1–Jβ2.6 primer sets, DNA from enlarged LNs of tertiary recipients shows only one predominant band (see arrow), indicating that lymphoma cells were monoclonal.