Flow cytometric analysis of aberrant antigen expression of blasts using CD45 blast gating for minimal residual disease in acute leukemia and high-risk myelodysplastic syndrome.

To evaluate the availability of quantification of blasts with aberrant antigen expression (AAE) using CD45 gating for minimal residual disease (MRD), 15 patients with acute leukemia (AL) and myelodysplastic syndrome (MDS) were studied. In patients with complete remission (CR), the frequency of blasts with AAE (%AAE) by CD45/side scatter (SSC) gating was significantly higher than that by the traditional forward scatter (FSC)/SSC combination (median, 4.1 vs. 0.3%, P<0.0001). We also demonstrated two representative cases, in which leukemia relapse could be predicted before 3 weeks and the early treatment for MRD could be performed for MRD after allogeneic bone marrow transplantation (BMT). These results indicate that this procedure is very useful for the evaluation of the quality of CR.