Flow minimal residual disease monitoring of candidate leukemic stem cells defined by the immunophenotype, CD34+CD38lowCD19+ in B-lineage childhood acute lymphoblastic leukemia.

Flow cytometric minimal residual disease (MRD) monitoring could become more powerful if directed towards the disease-maintaining leukemic stem cell (LSC) compartment. Using a cohort of 48 children with B-lineage acute lymphoblastic leukemia (ALL), we sought the newly proposed candidate-LSC population, CD34(+)CD38(low)CD19(+), at presentation and in end of induction bone marrow samples. We identified the candidate LSC population in 60% of diagnostic samples and its presence correlated with expression of CD38, relative to that of normal B-cell progenitors.

Establishment and validation of a standard protocol for the detection of minimal residual disease in B lineage childhood acute lymphoblastic leukemia by flow cytometry in a multi-center setting.

Minimal residual disease detection, used for clinical management of children with acute lymphoblastic leukemia, can be performed by molecular analysis of antigen-receptor gene rearrangements or by flow cytometric analysis of aberrant immunophenotypes. For flow minimal residual disease to be incorporated into larger national and international trials, a quality assured, standardized method is needed which can be performed in a multi-center setting. We report a four color, flow cytometric protocol established and validated by the UK acute lymphoblastic leukemia Flow minimal residual disease group.