IMMUNOPHENOTYPIC CHARACTERIZATION OF ACUTE LEUKEMIAS AND CHRONIC LYMPHOPROLIFERATIVE DISORDERS - PRACTICAL RECOMMENDATIONS AND CLASSIFICATIONS

Immunophenotypic characterization of leukemic cells has become essenti al for the diagnosis of acute leukemias (AL) and chronic lymphoprolife rative disorders (CLPD). Immunophenotyping allows to classify AL accor ding to (i) lineage assignement of the leukemic clone based on the deg ree of specificity (or ''score'') of expressed markers, (ii) the diffe rentiation level of the clone and (iii) the presence of irrelevant mar kers. In addition, some rare AL subtypes may be identified, such as M0 , M6 ''variant'' and M7 FAB types, as well as ''biphenotypic'' (hybrid ) AL. Finally particular immunophenotypic profiles are of pronostic va lue or associated with specific cytogenetic abnormalities, In leukemic phase CLPD setting, some circulating lymphoid cell immunophenotypic p rofiles are strongly correlated with morphology as defined by the FAB and REAL classifications. In addition, some marker expressions are of pronostic value. However, proper choices of sample nature, monoclonal antibodies and immunophenotyping methods are essential to improve qual ity, reliability and reproducibility of the results and must be carefu lly controlled in and between laboratories.