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.