[In Vitro Identification and Characteristics of CD34 Leukemia Stem Cell in t(8;21) Acute Myeloid Leukemia].

Objective: To preliminarily identify the existence of CD34 leukemia stem cell (LSC) in t(8;21) acute myeloid leukemia (AML) by in vitro test.

Methods: Bone marrow samples collected from newly diagnosed t(8;21) AML patients were tested. LinCD34 CD38(abbreviation, CD34CD38), LinCD34CD38 (abbreviation, CD34CD38) and LinCD34CD38CD45SSC(abbreviation, CD34"LSC") cell fractions were gated by flow cytometry after staining with fluorescent antibodies. Cells in G phase were identified through Hoechst 33342 and pyronin Y staining. Aldefluor reagent was used to test aldehyde dehydrogenase (ALDH) activity. The above-mentioned 3 cell fractions were sorted, and mRNA levels of AML1-ETO and WT1 were measured by real-time quantitative PCR.

Results: The 3 tested samples displayed the same tendency in ratio of the cells in G phase: CD34"LSC">CD34 CD38>CD34CD38. The paired t-test of 53 patients showed that frequency of ALDH cells of both CD34CD38 and CD34"LSC" cell fractions was significantly higher than that of CD34CD38 (P<0.01), furthermore, the ALDH cell frequency was significantly higher in CD34"LSC" than that in CD34 CD38 (P<0.01). AML1-ETO mRNA levels of cells sorted from 3 patients were similar among the 3 cell fractions within each patient, whereas WT1 mRNA levels were significantly higher in CD34"LSC" than that in other 2 cell fractions.

Conclusion: CD34 LSC may exist in t(8;21) AML, and may be more primitive than CD34 LSC. These results promote the necessity to perform in vivo xenogeneic transplantation mice.