Immunophenotyping of AML and MDS and detection of residual disease.

Immunophenotyping improves both accuracy and reproducibility of the FAB classification and is considered particularly useful for identifying poorly differentiated FAB subtypes of AML, such as AML with minimal differentiation (M0), microgranular promyelocytic leukaemia (M3V), and megakaryoblastic leukaemia (M7). Immunological studies of myeloid leukaemic blasts has become critical also in identifying biphenotypic leukaemias and AML expressing lymphoid-associated markers (Ly+ AML). At present, while the prognostic value of individual antigen expressions is still controversial, due to technical questions, the immunological detection of MRD seems to be important in monitoring AML patients in remission and, perhaps, in detecting leukaemic cell contamination into bone marrow or peripheral blood progenitor cells collected for autologous transplantation. In addition, the relationship established between genetic abnormalities and certain phenotypes within different FAB subtypes suggests that, in the future, immunophenotypical studies could be used for the screening of AML cases carrying specific genetic aberrations. Compared to acute leukaemias, little information is available concerning immunological patterns in MDS, and the role of the immunophenotype in diagnosis, subclassification, and prognosis of MDS is currently not well established.