Detection of minimal residual disease in acute leukemia by flow cytometry

Commercial flow cytometers can detect and enumerate rare cells at the level of 1 per 10(5) other cells within a reasonable measuring time, provided that the rare cells can be uniquely labeled with fluorescent marker. This detection level is sufficient for the enumeration of normal hematopoietic stem cells and committed progenitor cells. Detection at this level is useful for the quantitation of residual leukemic cells in remission bone marrow, for the analysis of the proliferative state of these cells as well as of normal stem cells, which are of importance in choosing the optimal chemotherapy regimen, and for monitoring the efficacy of maintenance chemotherapy. A further improvement in the speed of flow cytometers would be required, however, to make full use of the bone marrow samples.