Standardized Multicentric Quantimetry of Differentiation Antigens Expression. The GEIL'S Approach in Acute Lymphoblastic Leukemia

The use of flow cytometry as a common tool has opened the field of quantimetric immunopheno-typing. This could help refine the definition of leukemic proliferations, and perhaps provide new prognostic criteria. We investigated whether this approach could be applied to multicentric immunophenotyping. The reproducibility of quantitative measurements on different types of flow cy-tometers was tested using a single batch of calibrating and “blind” fluorescent beads. Less than 7% CV was obtained between 20 different laboratories. We then explored the variations noted with control or normal lymphocytes, using various CD4 monoclonal antibodies, which were found to be lower than 10%. We finally applied this strategy to acute lymphoblastic leukemias (ALL), performing quantitative measurements of CD 10 using one single aliquoted batch of FITC-CD10 in comparison with locally used reagents. PreB-ALL could indeed be further stratified depending on the density of CD 10 expression. Use of the same monoclonal antibody is...