New methodologic approaches for immunophenotyping acute leukemias

Background and Objectives. Flow cytometry is nowadays the preferred method for immunophenotypic identification, enumeration and characterization of bl ast cells at diagnosis. Despite widespread application of standardized prot ocols, inter-laboratory reproducibility has still not been achieved. The co mplexity of diagnosis and evaluation of minimal residual disease, in immuno phenotyping acute leukemia, demands the use of a test that provides all the necessary information. Data Sources and Methods. The information given here is derived from the ex perience of the authors and from literature files. The most relevant studie s with adequate conclusions were considered. We report on the current statu s of multiparametric immunophenotyping using simultaneous three and four-co lor staining and the applications of this technique. Results. Multiparametric immunophenotyping is a powerful method for achievi ng a clear discrimination between normal and pathologic cells. The specific identification of leukemic cells by immunologic gating forms the basis for immunophenotypic diagnosis, classification as well as prognostic evaluatio n of patients with acute leukemias. The performance of the procedure with r egards to the panels of reagents and the analytic processes, is necessarily different in lymphoblastic and myeloblastic leukemias, since the diagnosti c questions are different. Phenotypic information should be specifically pr ovided for the blast cells and antigen expression should preferably be repo rted in quantitative units and CV. This would allow a standardized cross ev aluation of immunophenotypic results between different investigators and la boratories. Interpretation and Conclusions. Recent reports indicate that phenotypic abe rrations reflect genetic abnormalities of leukemic cells and therefore thei r definition and identification is of clinical relevance not only for minim al residual disease monitoring but also for subclassifying acute myeloid an d lymphocytic leukemias. (C) 2001, Ferrata Storti Foundation.