[Detection of minimal residual disease in acute leukemias by flow cytometry]

Detection of minimal residual disease in acute leukemias by flow cytometry has become an interesting tool for the analysis of minimal residual disease in acute leukemias. Some complementary studies can be used for this purpose such as conventional cytogenetics, FISH and molecular biology (PCR and Southern Blot). Flow cytometry study can detect smoldering blast cells in patients with acute leukemias who appear to be in complete remission by conventional morphologic criteria (< 5% of blast cells in bone marrow aspirate sample). This method can recognize 1 blast in 10(-4) mononuclear bone marrow cells considering the characteristics of immunophenotype at diagnosis (aberrant, asynchronous and overexpressed phenotypes) or using the analysis cell maturation to identify normal and abnormal patterns. These differences can be distinguished when the cells occupy the 'empty spaces' where no normal cells are evident. The principal objective of detecting low levels of tumor cells is to obtain more information about the efficacy of the treatment in order to: 1) design adapted post-remission protocols for high risk patients, 2) predict relapses previous to the clinical manifestations, 3) study the quality of stem cells harvested for autologous bone marrow transplantation.